Include volume_metadata with object on vol create

Include volume_metadata with object on vol create

Fix for Bug 1029762

The symptom of this bug is that the response data of an
OSAPI create call always shows and empty dict for volume_metadata
regardless of what was passed in to created and actually used.

Upon the db create_volume call a reference to the volume
object is all that was being returned.  Since metadata is
specified and set, it should also be returned with the
create reference object.

This will result in the the osapi create call returning
a body with correct metdata info rather than always showing
and empty dict as it was previously.

Change-Id: I9ae9c737bd2aa5bfa14c19fe8b8b2a7a5aa4d43a