ATE-issue-8

Merge the code that solves issue #8 into test-framework. Those changes are:
* Overhaul of the TA/Lecturer automated testing UI to use AJAX
* Server-side code refactoring to handle AJAX requests
* Fixing of broken functionality (i.e. was unable to load Test Support Files)
* Fixed some model errors (i.e. uploaded test files not properly being deleted when replaced with a different file)
* Updated and fixed unit tests