Attempt to update the plugin to ES 5.1.1

[jcscottiii]

The PR is an attempt to update the plugin to work with ES 5.1.1

Need a new branch to target instead of 2.4.1

Extra stuff: My IDE found that some files used both tabs and spaces. As a result some of the files have adjusted some lines to use which ever style was prominent in that file. (not much logic changes)

Notable Changes

• Move from using handleRequest to prepareRequest. Commit it happened in ES Source
• Using Java 1.8 notation for channels and sendResponse. Example of it in ES Source
• Move the plugin from extends Plugin to implements ActionPlugin
  • Move from using onModule to getRestHandlers
• In ES Source, they moved from using ESLogger wrapper to log4j. This patch does so as well Commit in ES
• setRefresh was removed and replaced with setRefreshPolicy in ES. Did the same here. Example in Commit in ES when it was replaced
• Elasticsearch removed it's own Base64 implementation in favor of the one in Java java.util.Base64

[CLAassistant]

All committers have signed the CLA.

[jcscottiii]

Big TODO: Need to actually try this out

[lmangani]

This week is Epic! Thanks @jcscottiii Could you please point the PR at branch 5.1.1 (just a clone of 2.4.1) so we can merge & test it?

[jcscottiii]

@lmangani done! :)

[jcscottiii]

@lmangani any testing assistance would be great !! :)