Adding notes to service causes error on save

http://support.openlp.org/issues/2066

With 2.0.2 add a note to an item in the service manager.
Click File->Save: Follow traceback pops up:

--- Exception Traceback ---
Traceback (most recent call last):
   File "/usr/share/openlp/openlp/core/ui/servicemanager.py", line 546,
in saveFile
     service_content = json.dumps(service)
   File "/usr/lib/python2.7/json/__init__.py", line 233, in dumps
     return _default_encoder.encode(obj)
   File "/usr/lib/python2.7/json/encoder.py", line 203, in encode
     chunks = self.iterencode(o, _one_shot=True)
   File "/usr/lib/python2.7/json/encoder.py", line 266, in iterencode
     return _iterencode(o, 0)
   File "/usr/lib/python2.7/json/encoder.py", line 180, in default
     raise TypeError(repr(o) " is not JSON serializable")
TypeError: PyQt4.QtCore.QString(u'After the sermon.') is not JSON
serializable