Update README.md for zone clarity
Upgrade to Lucene 5.0.0-snapshot-1637347
update documentation with release 2.4.0
[TESTS] Upgrade randomizedtesting-runner to 2.1.10
(cherry picked from commit 87b1b25)
Update Google APIs to 1.19.0
Snapshot/Restore API: Add Google Cloud Storage support

Adds the ability to snapshot/restore indices to/from the Google Cloud Storage platform. This functionnality also works when the plugin is installed on a Compute Engine instance. The authorization process is based on "service account" files, which is the recommanded way to auhenticate application against the GCS service. This implementation uses the Google Storage API (v0.19.0), and the uploading of blobs are executed in a background thread.

Closes #11
Removing unused imports
Simplifies waitForCompletion() method
Add dedicated thread pool
Minor fix due to Lucene 5 update
Add documentation on GCS repository
Change inefficient implementation of GoogleCloudStorageOutputStream to use an internal BufferedOutputstream with a configurable buffer_size
Update GCS BlobContainer implementation because BlobContainer intefaced changed

See elasticsearch/elasticsearch#8366