Added some tests to rfctag class around Private Use Language, Script and Region subtags.
Added some tests to rfctag class around Private Use Language, Script and Region subtags.

chrisvire/libpalaso,gmartin7/libpalaso,tombogle/libpalaso,gtryus/libpalaso,chrisvire/libpalaso,JohnThomson/libpalaso,ermshiperete/libpalaso,tombogle/libpalaso,mccarthyrb/libpalaso,glasseyes/libpalaso,mccarthyrb/libpalaso,JohnThomson/libpalaso,marksvc/libpalaso,glasseyes/libpalaso,gmartin7/libpalaso,chrisvire/libpalaso,tombogle/libpalaso,ddaspit/libpalaso,gtryus/libpalaso,JohnThomson/libpalaso,ddaspit/libpalaso,marksvc/libpalaso,sillsdev/libpalaso,gtryus/libpalaso,sillsdev/libpalaso,JohnThomson/libpalaso,ermshiperete/libpalaso,andrew-polk/libpalaso,glasseyes/libpalaso,andrew-polk/libpalaso,glasseyes/libpalaso,darcywong00/libpalaso,ermshiperete/libpalaso,ddaspit/libpalaso,chrisvire/libpalaso,tombogle/libpalaso,gtryus/libpalaso,ddaspit/libpalaso,sillsdev/libpalaso,gmartin7/libpalaso,sillsdev/libpalaso,andrew-polk/libpalaso,marksvc/libpalaso,mccarthyrb/libpalaso,andrew-polk/libpalaso,gmartin7/libpalaso,hatton/libpalaso,hatton/libpalaso,hatton/libpalaso,hatton/libpalaso,mccarthyrb/libpalaso,darcywong00/libpalaso,darcywong00/libpalaso,ermshiperete/libpalaso