ATE-issue-8

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