Added documentation to keystone.common.dependency.

All public attributes now have docstrings describing their interface,
and the module has a top level docstring as well. Previously,
documentation was very sparse.

Closes-Bug: #1252428
Change-Id: I9c83883a6d9ae3201c9037c979689cb82c232120
Ensure the sample policy file won't diverge

Currently rules should appear in both policy.v3cloudsample.json and
policy.json. In the future there may be a few exceptions that can be
documented by making the exception explicit in the test.

Change-Id: I3e9cdf64998d667941c44dc6edb48c2f7a9d37c4
Closes-Bug: #1255564
Sync From OSLO

blueprint: key-distribution-server
Change-Id: I424dbd6e8a535279498589444b976ea332e09c64
Refactor assertEqualXML into a testtools matcher

Not all tests inheriting from TestCase will need to check XML equality.
Moving this functionality to a matcher leaves it up to the test class to
decided whether or not it needs it.

Change-Id: Ib28ec3b5dd96f662ce0cd90c650434b24c63ad6c
Related-Bug: #1226466
Merge "Sync From OSLO"
Merge "Refactor assertEqualXML into a testtools matcher"
Merge "Added documentation to keystone.common.dependency."
Merge "Ensure the sample policy file won't diverge"
Don't run non-tests

Some functions in keystone.tests.core were running that were not
tests because the name contained "test".

Functions that are not tests should not be run as tests, so these
functions were renamed.

Change-Id: Icb0f0186b2b20e7b6e5a42e068fde2b89e771741