Music service data structure tests

This is the first batch of unit tests for the data structures. The second batch might not be until after further improvements to the data structures, as there is still room for improvement there.
Mmmm. I had some problems getting this to work dur to various python 2.7 vs. 3 differences. In order to be able to make the comparison just afterwards, both strings need to be unicode. Easiest way to make sure they are that is to do an decode. At the same time, the strings needs to be formatted into the template needs to also be unicode, but have all of its non ASCII chars replaced with XML excapes. Well, this was the solution I ended out with. I don't know if there is a better way.