Code review comment for lp:~mvo/unity/sc-launcher-integration-fixes

Thanks again Marco!

I updated the code now to use DesktopUtilities::GetDesktopPathByID() and updated the tests and moved the init of the XDG_DATA_DIRS into test_main.cpp. Both the automatic tests and manual tests with applications from app-install-data-ubuntu and from purchases in the software-center work for me now with animation, update on finish to the right app and error handling (i.e. removal on cancel etc).