Add Google BigQuery output plugin

This pull request adds plugin to export data to Google BigQuery. This plugin uses similar approach to Google Cloud Storage, but adds some additional logic (like deleting local buffer file only if job - which is asynchronous - is completed).

This pull request also fixes a few things in the Google Cloud Storage plugin related to gzip support and fsync/flush.

(This plugin requires the patch posted on LOGSTASH-1334 issue to work in a JAR.)