First phase of migration to using composites for Compute tests

* Replaced all instances of config/client generation with properties
  from the compute composite. The next phase will try to collapse
  the fixtures completely
* Fixed variable references where necessary
* Modified authorization test to allow it to generate the necessary clients

Change-Id: I7cdd4daa535d8fd71e0bdf7ec9116465bece1a2d
Merge "First phase of migration to using composites for Compute tests"