Add google_cloud_storage output plugin and google-api-client gem.
Rename plugin to google_cloud_storage.
Merge remote-tracking branch 'upstream/master'
Add key_password and uploader_interval_secs config options to Google GCS plugin.
These configuration options allow the GCS private key password if the user changed it and how frequent the uploader will run based on the time pattern used in the plugin configuration.
Merge pull request #572 from rdcastro/master

Add google_cloud_storage output plugin and google-api-client gem