MatchMakerStub - make it work & add test

The super() in MatchMakerStub.__init__ was
referencing the wrong class due to copy/paste.

I've also added a test for this class.

Fixes bug 1185501

Change-Id: I298c8c1df4dcb3d3e905ecbb5400d16b3383fdf9
Merge "MatchMakerStub - make it work & add test"