[Verify] Reworking unit tests for config.py [part 1]
[Verify] Reworking unit tests for config.py [part 1]

1. The setUp() method was reworked
   because no one could understand how it worked.
2. Now ddt module is used where it is possible.
3. Some tests were refactored.

In some tests you will see that

    self.assertIn(sorted(expected)[0], sorted(result))

was replaced by

    for item in expected:
        self.assertIn(item, result)

because sorted(expected)[0] is only the first item from expected tuple.
So we always checked only one item from config section. The wrong behavior
was introduced by the following commit: I487806fe9a8ccd8528922cfaa2700df30961ef9b.
Now it is to be fixed.

Change-Id: Iaabc1a9fbd77e73bd9d28a30b29f9827a22e0bbd

amit0701/rally,amit0701/rally,gluke77/rally,openstack/rally,vganapath/rally,vganapath/rally,gluke77/rally,eayunstack/rally,eayunstack/rally,gluke77/rally,amit0701/rally,gluke77/rally,openstack/rally,openstack/rally,group-policy/rally,eayunstack/rally,group-policy/rally,eonpatapon/rally,yeming233/rally,yeming233/rally,vganapath/rally,openstack/rally,eonpatapon/rally,group-policy/rally,vganapath/rally