Closes #17

Closes https://github.com/erocci/erocci/issues/67

Should fix https://github.com/erocci/erocci/issues/66

Exception: <<"Traceback (most recent call last):\n  File \"/usr/lib/python3/dist-packages/dbus/service.py\", line 707, in _message_cb\n    retval = candidate_method(self, *args, **keywords)\n  File \"/home/travis/build/erocci/erocci_backend_dbus/test/dbus_python_SUITE_data/erocci_sample_backend.py\", line 187, in Link\n    log(\"Link(%s, %i, %s)\" % (location, direction, link))\nSystemError: ../Objects/bytesobject.c:2931: bad argument to internal function\n">>