./setup.py check now invokes tests in tests/ directory. tests directory should
have integration(UI tests) and unit(unit tests) sub directories, but it isn't
necessary to have any dir. of the above.
It needs to be called as early as possible before unit tests
has a chance to import gtk.
Hopefully will fix random test failures we are seeing in buildbot.
This ensures the test itself is not recognized as a client
by the registry. I'm not sure how that happens since we are
not loading gtk, but it does. Not being a real gtk client with
a mainloop we wasn't answering dbus calls and causing the registry
to hang and fail.
