* add and fix up day11 assignment (craigslist scraper)
* fix reference to assignment from lecture html
* bolt day11 assignments into the assignments index.html
use the 'hidden-code-block' sphinx extension to make easy show/hide code blocks for a more try-it-yourself approach to the follow-the-path assignment structure.

see https://github.com/scopatz/hiddencode
and http://scopatz.github.io/hiddencode/