2.5.0.0-alpha4 release with support for ES 5.0.0-alpha4

This is a preview release of the plugin for Elasticsearch 5.0.0-alpha4 with improved setting validation, better security management, and fixes for the deprecated onModule method.

To install the plugin, run:

bin/elasticsearch-plugin install -b https://github.com/couchbaselabs/elasticsearch-transport-couchbase/releases/download/2.5.0.0-alpha4/elasticsearch-transport-couchbase-2.5.0.0-alpha4.zip