Add v2 Token manager authenticate tests

This function is currently completely untested. Create tests to
reinforce behaviour.

Change-Id: I8cfbea37964e3d96cc444ad6f62542786429e44b
Test that tenant list function can use auth_url

Listing tenants can be done on the auth URL because it is often needed
to be performed with an unscoped token. The behaviour is not tested
though so add a test to cover it.

Change-Id: Ic14d54f0f1d8cca2c3a5a6a6da7465c703773aa0
remove useless part of error message

also did a bit of code cleanup for consistency

Change-Id: I48832c36e1a8b5a0029598dc74aaeaa3b3d2a66f
Fix mistakes in token fixtures

There are two small mistakes i discovered in the token fixtures. Fix
these and add a bunch of new tests that would have caught them earlier.

Closes-Bug: #1342513
Closes-Bug: #1342515
Change-Id: I7c07bd915fd84cc77cae0004220d8bb8d79bb082
Merge "remove useless part of error message"
Merge "Fix mistakes in token fixtures"
Merge "Add v2 Token manager authenticate tests"
Merge "Test that tenant list function can use auth_url"