Move Keystone config to main designate config

The keystone middleware can be configured using the main designate
config file. This allows the api-paste config file to be left as is
by most designate users.

Bug #1206091

Change-Id: I6b0be7dbdecdecd5579b3024b59d8a070205fc1e
Merge "Move Keystone config to main designate config"