When the keystonemiddleware is used directly in the WSGI stack of an
application, the 503 that is raised when the keystone service errors
or cannot be reached needs to identify that keystone is the service
that has failed, otherwise it appears to the client that it is the
service they are trying to access is down, which is misleading.
This addresses the problem in the most straightforward way possible:
the exception that causes the 503 is given a message including the
word "Keystone".
The call method in BaseAuthTokenTestCase gains an
expected_body_string kwarg. If not None, the response body (as
a six.text_type) is compared with the value.
Change-Id: Idf211e7bc99139744af232f5ea3ecb4be41551ca
Closes-Bug: #1747655
Closes-Bug: #1749797
d3352ff422