Unit tests as stress tests

Creating a special stressaction, which is able to call an
arbitrary existing unit test as stress action.

The setUpClass() and tearDownClass() can happen in every action,
 or just once per thread or once per stress application run,
 it is configure able option.

Change-Id: Ia5432a4d9d749aa7618e098d8eeedd70d00b0b6d
Skip os-fixed-ips test since neutron has not implemented it

Change-Id: I4ad35c994e8eb1038c7ef91f604d8fa4b9db421f
Closes-Bug: #1214199
Merge "Unit tests as stress tests"
Merge "Skip os-fixed-ips test since neutron has not implemented it"