mandos: Stop using str() and remove unnecessary unicode() calls.
* mandos (if_nametoindex): Use "bytes" literal instead of str(). (initlogger): Use a unicode string for log device. (AvahiError.__unicode__): Removed. (DBusPropertyException.__unicode__): - '' - (ClientDBus.Secret_dbus_property): Use bytes() instead of str(). (IPv6_TCPServer.server_bind): Use .encode() instead of str(). (string_to_delta): Removed unnecessary unicode() call. (main): Use "isinstance(x, bytes)" instead of "type(x) is str", use .decode() instead of unicode(), and use .encode() instead of str().