Add tests for getting nova api version details

This commit adds the necessary client and test bits to verify that there is
an api version detail response from all the versioned urls presented by the
GET of the top level version document.

Co-Authored-By: Sean Dague <sean@dague.net>

Change-Id: I70294329870de46b2c4c8775a1d7920bee403954
Depends-On: If2ce6c9c9e2fde554b4e44dc99ec70d087c3f682
Related-Bug: #1491579
3 files changed