gluster: dao changes for volume capacity info

  Adding Details table for Gluster Volume and Brick
entities.  Necessary DAO changes were made to update/read
the capacity information for brick and volume.

Change-Id: I7d67b7ee22f4cb6839d0f14d3f27f3e22149ff22
Signed-off-by: Ramesh Nachimuthu <rnachimu@redhat.com>