Add the volume and snapshot gigabytes together.

The quota sync functions were not working correctly for both
snapshots and volumes regarding gigabytes. Each would report
their own count as the total gigabytes.

Now the gigabytes sync is separate from the volume and snapshot
count syncs.

Fixes bug #1160004

Change-Id: Ib1200813acb6055412b3f7f6b63fa9ba2b8fa3be
Merge "Add the volume and snapshot gigabytes together."