Slightly prettier and more meaningful coachreports for exams

Interface improvements:

* colored circles instead of big rectangles to indicate status
* not started (blank) differentiated from incomplete (gray) 
* helpful info for incomplete (gray with score & title tag shows number remaining) 
![selection_085](https://cloud.githubusercontent.com/assets/1319950/4279669/72289692-3d23-11e4-858e-cdf3a04bcece.png)

If you want I can add the styling with the circles into the tabular reports as well, but didn't want to touch them without the go ahead. 

@jamalex 
Wowzers!