Fix a bug in the Makefile.

(The tutorial creation script needs to delete files before recreating them.)
Merge pull request #27 from CSSE1001/tests_framework

Added new tests framework (which runs arbitrary code in the student's context) and updated tutorial problems.
Merge pull request #28 from CSSE1001/tests_framework

Added error detection and highlighting in UI
Now correctly handles FileNotFoundError

(Well, not so much handles as ignores, and rebuilds the config from
defaults.)

This mistake was due to the upgrade from Python 2, which used IOError.

See #29
Finally squashed the bloody CRLF files
Message wrapping is now part of TestResult
Added todo note re: refactoring