Heat services need keystoneclient not keystone

The common recipe has been pulling in the entire
python-keystone package, which is the entire Keystone
set of services. This hasn't been necessary since
some time after Grizzly, when the tokenauth middleware
was moved to the client.

Change-Id: Ifb133d570e2ad94df822aa512edeb37aabdf349b
Related-Bug: #1305318