contents list implementation, styles - some mobile

I have finally implemented the contents list for assignment pages. It's
looking alright, but it needs tweaks.

Styles have naturally been changed in the process, accomodating the new
markup.

I noticed a small grammatical error on 2.3, which was corrected.

I also added a mobile stylsheet and meta tag. Although far from perfect,
these make it a little more bearable on a small screen. I will develop
this further at some point.