Configure Parsoid logging on betalabs to logstash via bunyan/gelf-stream.

* Added the gelf-stream package to the deploy repo.

* Tweaked betalabs.localsettings.js configuration for Parsoid
  to use gelf-stream to get our logs to logstash in gelf format.

  Continue to dump to stdout as well.

* Will update production based on experience with betalabs.

Authors: C.Scott Ananian, S.Subramanya Sastry

Change-Id: I18b765db44bd387fefae9145e97b3481fd81ddd6