Add container namespace mapping
    
    The container namespace in DistGit/PagkageDB has migrated from
    "docker" to "container" in order to keep it more generic than
    a specific implementation. This update adds support for the new
    namespace mappings. Note that we will no longer add mappings to the
    "docker" namespace mappings and will eventually retire it from this
    script once they are no longer needed.
    
    Signed-off-by: Adam Miller <maxamillion@fedoraproject.org>