Fixed identation bug.
Custom exceptions for MyData.
MyData is beginning to make use of MyTardis's new Instrument
model.  More work is needed, particularly in relation to
defining default experiments based on instrument, data collection
date, and data owner (see ExperimentModel.py)
Minor additions needed for instrument-related queries.
- New method for setting the instrument(s) in an uploader record.
- Using upper camel case for class method. See here for an
interesting discussion on wxPython coding style:
http://wxpython-users.1045709.n5.nabble.com/Code-style-amp-arguments-to-event-handlers-td2365595.html
Improving validation of MyData's settings.