Merge pull request #383 from code-dot-org/levelTests

Support for turtle tests
incorporate additional piece of feedback from last pull request
Merge branch 'master' into levelTests
allow customizable timeouts, dont timeout if debugging, searchable test names so you can run single tests
Change mochatest grep to convert the string it's given into a regex
cache/reset some of the level info that changes over the course of running a test
Add a bunch of level tests
add comment to test.js regarding test times