standard-test-rhts: add support for beakerlib-libraries
    
    This patch adds optional resolving of test dependencies, including
    beakerlib libraries from beakerlib tests' Makefile. Note that the
    resolving of dependencires is required for beakerlib libraries (because
    they are packages without dependencies). To activate this feature pass
    to the role this variable:
    
    use_beakerlib_libraries: yes
    
    By default this feature is disabled (we might enable it after testing).
    
    Signed-off-by: Miroslav Vadkerti <mvadkert@redhat.com>