test/test_framework: Updated examples, a bit of better descriptions, sample partial solutions, etc.
Added all sample subject material. This has been copied from test/test_framework and modified slightly. There is now a subject "sample" with 2 worksheets. The 1st worksheet has 3 exercises. These work in IVLE by default.
setup.py: Added code to install subjects into the designated directory. This means that installing IVLE will result in the sample subjects being immediately available.