gluster: Sync gluster service statuses

Periodically fetches the status of gluster related services, and updates
the database with new statuses. The existing refresh interval defined in
the option GlusterRefreshRateLight is used for scheduling the job.

Change-Id: I312cacf698cb3420e30d96c42a92959b257c4abd
Signed-off-by: Shireesh Anjal <anjalshireesh@gmail.com>