Addition of base Smoke and Whitebox tests

* Splits out the "manager" class into its own file (at least
  for now to keep the code change size down initially)
* Adds base manager classes for Fuzz and Default clients
* Adds base test case class and a derived base SmokeTest class
* Adds smoke test for basic server operations in compute
* Adds non-smoke test for advanced server operations in compute
* Adds Whitebox base test case class
* New basic db-checking whitebox tests for servers and images

This change builds upon the proposed refactoring to the Tempest Manager
and base test classes as per https://review.openstack.org/#/c/7069

Change-Id: I12125fffb725cad3a4fef3134c83e55437529252
19 files changed