Workaround for bug 816

Identified the root cause of bug 816 as a race condition in Juju 2.6.6,
which will be fixed in the pending 2.6.7 release. In the meantime, this
adds a workaround to dealing with the race condition by sleeping
immediately after the model is created.

Change-Id: Ief3d0bffe51cef0736f9819a2934e62412584fe4
Signed-off-by: Adam Israel <adam.israel@canonical.com>