Fixing subproject test runs

The sahara declaration was missing in
openstack_dashboard/api/__init__.py.  This change adds the import and
adds 'sahara' to __all__ which should fix the test runs.

Change-Id: I7ba8b17aa4dc95d17fe83a2427a058d67e8e7afe
Closes-Bug:  bug 1340429
Merge "Fixing subproject test runs"