Add multiline output to file

[kvls]

We use logstash to collect some logs in a file in some format. And we need to have a certain format logs, for example: "%{message}\n%{status}\n%{level}". But file output not supports this format, and all '\n' becomes '\n'.

[elasticsearch-release]

Can one of the admins verify this patch?

[wiibaa]

Root issue is #1645

[jordansissel]

Closing this in favor of #1645 which will solve this problem. Let's continue the discussion on #1645! :)

[jordansissel]

For Logstash 1.5.0, we've moved all plugins (and grok patterns) to individual repositories. Can you move this pull request to https://github.com/logstash-plugins/logstash-output-file?

This sequence of steps may help you do this migration:

1. Fork this repository

2. Clone your fork

   git clone https://github.com/kvls/logstash.git

3. Create a branch:

   git checkout -b my-branch-name

4. Apply the patches from this PR into your branch:

   curl -s https://github.com/elastic/logstash/pull/1001.patch | git am

   This should take your commits from this PR and commit them to your new local branch.

5. Push!

   git push origin my-branch-name

6. Open a new PR against https://github.com/logstash-plugins/logstash-output-file