Automatically make first user account administrator

The first user to authenticate is now placed into the Administrators
group, making it simpler to bootstrap the server by having at least
one user who can modify permissions through the web UI, or create a
Git repository over SSH.

Change-Id: I8b39caaa129b3d0f693e0227fc3669ef18ca0df0
Signed-off-by: Shawn O. Pearce <sop@google.com>
3 files changed