etcd3 fixes

Fixes #19 and #26 around etcd3. Kudos go out to @pablokbs for all the hard work here to make this happen!

Fixes UI issues and a couple of minor things

Mainly addresses #7 and a few other things. Thanks @debben for the PR!

Fixes OpenShift deployment and #9

Fixes the OpenShift build/deploy commands after app reorg as well as addresses #9 .

Overwrite auto-discovery in app

Now the overwrite auto-discovery feature is also available in the app (Web UI), in the Configuration tab:

Filter in app

With this release the filter backup strategy is now also available in the app (Web UI) and not only in rcli anymore.

Introducing overwrite auto-discovery

As proposed in #4 you can now overwrite ReShifter's auto-discovery for backups, restores, and stats. This means effectively that when you use the RS_ETCD_API_VERSION environment variable, you de-activate the auto-discovery and force ReShifter to use a certain API (either v2 or v3).

For example with the CLI tool rcli, imaging you have an etcd3 cluster running but want to restore a backup using the v2 API:

# restore the backup with ID 1500628848 into your etcd3, but using the v2 API:
$ RS_ETCD_API_VERSION=v2 rcli restore -i 1500628848

Initial support for filter backup strategy

Now with an initial version for the filter backup strategy. More details and examples to follow. Hint: use RS_BACKUP_STRATEGY env variable ;)

Also: fixes a bug in rcli stats command.

Bug fix for discovery bug

There was a nasty logical bug (fixed in 1db5416) that caused key stats not to work properly. This release now should address #2 and #4 and in addition work correctly for every combination of etcd version (2|3) and API version (2|3).

Yet another bug fix release

Towards #4 re the stats part

Another bug fix release

Addresses #2 and #4