Proxy Assignment from Identity Deprecated

The identity_api served as a proxy for calling the assignment_api
and a majority of this proxy mechanism was removed.  This is the
second pass on the proxy cleanup fixing up the lingering domain
calls from the identity core api.

All proxy calls removed in the Icehouse development cycle (so far)
have been re-added and now have the @deprecated mechanism used to
indicate the support will be removed once development for J release
has been opened as discussed at the Icehouse design summit. See
https://etherpad.openstack.org/p/icehouse-keystone-internal-apis
for information on why these were added back in.

closes-bug: #1220913
Change-Id: If28b6d9189fa5879c8dbe131174b8cb8f84d9668
Merge "Proxy Assignment from Identity Deprecated"