Update to version 1.3.0
    
    New Public Objects:
      * Modulemd.Prioritizer tool to merge module defaults
    New Public Functions:
      * Modulemd.SimpleSet.is_equal()
      * Modulemd.Defaults.copy()
      * Modulemd.Defaults.merge()
    
    Signed-off-by: Stephen Gallagher <sgallagh@redhat.com>