HTML report now includes snippets from source files

**Squashed commits of #42**

Uses the pygments library to include snippets from source files showing which lines are uncovered.

It looks like this:
![image](https://f.cloud.github.com/assets/2948394/989509/eb748fa8-0915-11e3-862b-0fd754e7441d.png)

Currently, this is implemented only in the coverage report, not the quality reports.

This PR also includes pylint/pep8 fixes and clean up for allowing the test cases to load fixtures.

Suggested reviewers: @sarina @jzoldak