Minor lab cleanup

This fork has a few minor changes that would've made my life easier at the time I ran through the labs.  I thought perhaps others who have yet to work through the labs might find these changes help as well.

- Formatted using typesafe's sbt-scalariform plugin
- Fixed a few typos
- Fixed tests that were failing or not running when they should have been passing
- Broke up and reordered exercises in advanced/lab03, added reference for the "Mammals" problem