Private flavors dont get tenants assigned by default

When a private flavor is created (Is_Public = False), nova does
not assigned any tenant to the flavor by default. Users should use
the adding/removing apis for that matter.

Change-Id: I654fcf008a8459e55d0d0a634e08ddc9609d7a03
Closes-Bug: #1295818
Merge "Private flavors dont get tenants assigned by default"