Rewrite tests from VNC to RDP
    
    The VNC installation method has been replaced with a similar method
    based on RDP. This PR uses the old mechanism and alters it for the
    RDP method.
    
    The test suite consists of two parts, a server and a client part.
    The server is the real test on which Fedora Custom installation
    is performed from the client via RDP.
    
    The client is spinned off the pre-installed desktop image.
    
    Fixes #345