fix broken when non-ASCII in path
    
    Path can be got from current directory or the --path option. In both
    cases, unicode string is used instead of byte string.
    
    This change is compatible with Python 3 by defining pyrpkg own's u and
    getcwd methods, that is because it's necessary to convert path specified
    via --path option from byte string to Unicode string in UTF-8, and get
    current directory as Unicode string. So far, six.moves.getcwd is only
    supported in 1.10.0 which is available for fc24, thus, six.moves.getcwd
    is not available in any old distros using older version of six.
    
    This is related to the fix of bug 1286374.
    
    Signed-off-by: Chenxiong Qi <cqi@redhat.com>