Simplify running tests
    
    There is no need to run the tests both by setup.py and nose: it just
    runs the same tests twice. Also, generating coverage data is useless and
    it will not be visible anywhere anyway. This allows us to get rid of one
    build requires.
    
    Also we should first run unittests and only then build the data for
    dummy compose: if the tests fail, we get the info earlier.