Load app before loading legacy client in tests.

When you load an old version of keystoneclient doing legacy tests and
then start the test app the ec2 work that depends on keystoneclient sees
the recently loaded legacy one which doesn't have the required modules
in it.

If we load the app first the ec2 modules are resolved and finds the
original keystone client. The ec2 module then uses
'from keystoneclient.contrib.ec2 import utils as ec2_utils' so the
ec2_utils reference is kept in the file scope so isn't affected by the
tests changing keystoneclient.

It is not a long term fix for bug 1178532 but it solves the immediate
symptoms when running client tests independently.

Change-Id: I7267ca0d4740f037884fae95f8a6562ee86584b9
Deprecate kvs token backend

This backend is not usable in any production environment. All OpenStack
environments will already have a SQL DB, and if someone does not want to
use the DB they can use the memcache backend.

Fixes bug 1188301 and bug 1188370

DocImpact This backend should not be mentioned in documentation, as it
is not production grade and is deprecated.

Change-Id: I41b147bcc70b79b4fc6df50b242a73cfcad33114
Use assignment_api rather than assignment

When normal dependency injection is used the variables
are named like "xxx_api".
This change makes it so that the identity backend and
drivers use "assignment_api" rather than "assignment"
so it will be easier to switch to normal dependency
injection.

Part of fix for bug 1200769

Change-Id: I7805b338c48d57ca1922bb622a3f474f2341f4ac
Merge "Load app before loading legacy client in tests."
Merge "Use assignment_api rather than assignment"