Use AccountGroup.UUID instead of Account.Id

By switching to the UUID we can have a globally unique identifier
for group membership throughout the server, even if group information
comes in from a different data source.

Change-Id: Icb49d6a6aff8e62864ac0f78ceedbe03f01de894
Signed-off-by: Shawn O. Pearce <sop@google.com>
49 files changed