Properly handle Regions in keystoneclient

Region name is taken as a parameter but is ignored in all communication
with the service catalog. Currently region can be stored in the token
data and then requests to url functions will return the appropriate
region. This is the wrong approach because there is nothing specific to
the token (or auth_data) that is region specific. Instead region
information should be held by the client.

Closes-Bug: 1147530
Closes-Bug: 1255992
Change-Id: I812aa89c8b4af28e294e63926a7f88e8246fffc5
Merge "Properly handle Regions in keystoneclient"