Cached tokens aren't expired

The auth_token test said that the cached tokens are expired. The
tokens weren't expired, so remove the code.

Change-Id: I8ce30cc09ee9bbc19cc4ebdb5d935a80d2d5d473
Move auth_token tests not requiring v2/v3 to new class

The tests in CommonAuthTokenMiddlewareTest run for both v2 and v3
tokens, but contained tests that weren't affected by the token
version.

The tests that aren't affected by the token version are now in
their own class.

Change-Id: I0e8aecafcd8e0da262dded48a612c84b1629d953
Remove importutils from oslo config

The importutils module is only used by other oslo modules, so
remove it from openstack-common.conf. It'll be pulled in
automatically if it's needed.

Change-Id: Iaa7e047a9ff76f911f8c64b45ceb1f240855670a
Sync with oslo-incubator 2640847

Sync with oslo-incubator commit
2640847e3df7720457103d2111846c27fc8fdcd5 .

First, remove the existing code to cleanup:

 $ rm -r keyestoneclient/openstack/*

Then, sync from oslo-incubator:

 $ python update.py ../python-keystoneclient

Change-Id: Ic94906002e0257ffc56245e49890e7ee2f3b4a2a
Merge "Cached tokens aren't expired"
Merge "Move auth_token tests not requiring v2/v3 to new class"
Merge "Remove importutils from oslo config"
Merge "Sync with oslo-incubator 2640847"