Added frontend/configtool related unit testing and refactoring improvements

This pull requests aims to address the outstanding TODOs inside of the frontend configtool related classes

Related #484 
I am not sure, the documentation is missing for the two functions - http://pyqt.sourceforge.net/Docs/PyQt4/qcombobox.html#currentIndex. I would assume there is a non-None default value that would be returned then.