Add missing reference to test project after upgrading to XS 5.2.
After upgrading to XS 5.2 running the tests would fail with TypeInitializationException with a reference to a type from this dll.

Also, XS 5.2 made modifications to repositories.config, I thought it best just to include them.
Merge pull request #651 from rojepp/xs52tests

Add missing reference to test project after upgrading to XS 5.2.