Updated to new Coursera format

- Updated CSS selector class names to reflect updates to Coursera
- Fixed file names for lectures named with &nbsp; and &quot; fixed in escape_name()
 - Shifted call of escape_name() to precede strip()  (avoids unnecessary spaces)
- Includes unpulled patch by jmorenoamor (https://github.com/dmotitsk/coursera/pull/7)