Nova API services need keystoneclient not keystone

The API service recipes have 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.

Closes-Bug: #1305318

Change-Id: I75ff23847936bb288ea49ca41d1e46edb5bd7730
Merge "Nova API services need keystoneclient not keystone"