Use testtools as the base testcase class.

Use testtools as the base unittest test case class towards to
parallelizing the test runs. Catch places where setUp and tearDown
were not being chained properly, and fix these problems.Remove
custom skip, using testtools.skip instead. Add TestResourceManager.

Part of blueprint speed-up-tempest

Change-Id: I8e7b5686b22969a0f3db96100a357c93a4d5c03f