Manages languages that are available and is responsible for loading translated
content at the granularity of a plugin.

To be done:
 - APIs for store and retrieval

Setting the path for storing the bundled language translation files to
<KIBANA_INSTALL>/data/store_translations/<PLUGIN_NAME>

To be done:
 - Better error handling in APIs
 - Fix threading issue with storePluginLanguageTranslations API

…vely

Updates with review comments from @srl295. Changed export syntax to show the
exported functions at end of file.

To be done:
 - Add algorithm to decide on the language for a plugin by comparing the accept languages
from the REST call and the plugin supported languages
 - Add REST API tests

…tions

Client would pass languages used in the 'accept-language' header. These
languages would then be compared against the plugin supported languages
and best compared language would be selected.

To be done:
 - Add REST API tests

… language

The register API is updated to be independent of plugin name and language. The API will now
traverse the path given and create language bundles as per language files it traverses.
The translations files structure has also been simplified to be just key/value objects.

To be done:
 - Add hapi API to get translations
 - Extend the API tests to test responses

From review elastic#7545 (comment)
following comments updated:
- README, .gitignore, and .eslintrc are not needed in a core plugin
- package.json only needs name and version
- unit tests need to go in a tests directory otherwise they won't get picked up
by the grunt tasks. Also our convention is to name the test file with the same
name as the module it's testing (so i18n_tests.js should just be i18n.js)
- For consistency with the rest of the code base, rename the data directory to fixtures.
- Prefer const (or let if necessary). Don't use var.
- Use ES6 imports/exports rather than commonjs style
- Only export the i18n module's public API. For instance, I don't think getPluginTranslationDetails is used outside of the i18n module, so it shouldn't be exposed publicly. If you want to expose it for testing purposes, I would recommend creating an i18n directory with an index.js file that exports the module's public API, and a separate i18n.js file with the "private" API. index.js will be for public use, i18n.js will be for private internal use.

From review (elastic#7545 (comment)):
- i18n module API should return promises for async operations instead of using
callbacks
- All filesystem access should be async
- Unit tests need to be updated based on new proposed plugin structure
(single language file, not split by view)

From design (elastic#6515 (comment)):
- Removed API as will consider in later phase

TODO:
- Make write function async

Updated write function to be asynchronous

…argument

The API originally took the directory as the argument but following reviews it
was decided to change to absolute file because it will be less brittle
since it is more explicit.

Translates the start-up message (“Kibana is loading ...”)in the Jade template.

To be done:
 - Means to register the core plugin translations. They are currently added
in the fixtures directory as static files. Need to be generated on the fly.

Task which calls registerTranslations API and then a task which copies the
regsitered translations to <kibana_root>/build/kibana

Registration of the core plugin translations during development start of
Kibana server. The translations include the welcome message and server error
startup message.

The UI when loading asks i18n plugin which language translation to use
depending on the user preferred language header 'accept-language'.
This commit is to handle scenario where header is not passed. The algorithm
then chooses the default language.

…gin init phase

This change follows review comments in:
elastic#6515 (comment)

Comments:
- elastic#7545 (diff)
- elastic#7545 (diff)

This require to use <kibana_root>/data for registered translations
and i18n plugin moved to core_plugins from plugins.

Refer to PR for more details:
elastic#7562

After review discussions it was agreed to just register the absolute paths
to translation files rather than bundling each file into one central file
at registration.

This commit contains the following review comments:
- elastic#7545 (diff)
- elastic#7545 (diff)
- elastic#7545 (diff)
- elastic#7545 (diff)
- elastic#7545 (diff)
- elastic#7545 (diff)
- elastic#7545 (diff)
- elastic#7545 (diff)
- elastic#7545 (diff)

The following review comments are included in the commit:
- elastic#7545 (comment)
- elastic#7545 (comment)
- elastic#7545 (comment)

Plugins should call the i18n plugin APIs through the server object
and not directly from the module.

This closes he following comments:
- elastic#7545 (comment)
- elastic#7545 (comment)
- elastic#7545 (comment)

Module version 1.2.0 fixes issue:
opentable/accept-language-parser#8

This commit updates review comments:
elastic#7545 (diff)
elastic#7545 (comment)

Adds 'defaultLocale' configurable item to the i18n plugin configuration.
The default locale is used for translations if the locale specified by user
is not supported.

This commit satisfies the review comment:
- elastic#7545 (diff)

This commit better structures the i18n capability so that it can be called
in UI code in a clearly defined fashion with minimum code. It also fixes
potential race conditions.

This commit updates review comments:
- elastic#7545 (diff)
- elastic#7545 (diff)
- elastic#7545 (diff)

The default language translations are loaded and are compared against the selected
language translations. The comparison can then highlight any missing translation
keys and can load the default translations keys as needed. This helps to unsure
where possible that a translation string is available in most scenarios even if not
in the locale requested.

This commit resolves review comments:
- elastic#7545 (comment)
- elastic#7545 (comment)

This tool helps to check that translation keys are translated. This tool can be
used for non-angular translation constructs like the Jade templates.

Updates for review comments:
elastic#7545 (review)

Update for review comments:
elastic#7545 (review)

To be done:
- Update of unit tests for UI and server
- Call of verify translations

There was a number of changes to the i18n module and the ui i18n wrapper
following review comments. This commit is to update the unit tests with
respect.

It was testing the static translation files. It is now updated to
test the translations registered when Kibana server is started and
the plugins have initialized.

Updates following review comments:
elastic#7545 (review)

This commit contain updates after the following review:
elastic#7545 (review)

Updates for review comments:
elastic#7545 (review)

Updates for the following review comments:
elastic#7545 (review)

Updates after the following review comments:
elastic#7545 (review)

Loading message changed following merge of commit
elastic@26c53e8#diff-e25d7fee746a4f249e17f87c02fd95f8R55
This required update to the welcome message and how it is called.

Updated the following review comments:
elastic#7545 (review)

The algorithm to return which locale to use for translations based on the user
locale list and the regsitered locales is updated in this commit. The algorithm
previously did an exact match on all the user locales first before (by priority)
then checking for best case match. The algorithm is now modified to check each
user locale starting with the highest priority first for an exact match and then
for best case match. If no match it then moves to the next user locale with
the next highest priority. This is to follow the priority list that a user
browser is configured for where there maybe a locale translation available
but might not be the exact match with regard to the locale code and/or script.
An example of this is that the highest priority locale of the user is 'en-US'
but the locale translation available is 'en'. It is better select the 'en'
locale rather than select the next highest locale which is an exact match.

Updates after the following reviews:
elastic#7545 (review)
elastic#7545 (review)

Change in the flo and layout of ui index meant that acceptLanguages were not
being passed. This commit is an update to fix this so that the welcome
messages are loaded.

This commit is for updates after the following review:
elastic#7545 (review)

When unit tests are run on a test server (like in the CI), it will start
Kibana server and register the core translations. This means that the i18n
unit tests need to be able to store the existing registration prior to
testing and replace after testing.

…one process

Moving the i18n module into a class so as to encapsulate the registered
translations which means there can be different and distinct instances per process.
This is to accomodate the user case where there might be multiple Kibana server
instances in a process and the localization should be at the server level.

Message starting with 'Give me a moment...' is no longer part of loading
message folowing a rebase with master.

- Update after following review: elastic#7545 (review)
- Also, fix syntax mess following rebase with master of src/optimize/index.js