Run JSHint on test files and fix issues 

- Added seperate JSHint target so options for tests don't interfere with those chosen for the source files
- Added watch task so tests are validated and qunit is run when they're modified
- Purposely excluded r.js and the testing libs

Also removed the old-modernizr file since it only contained a header.

PS: QUnit is currently on 1.11, but the embedded copy is using 1.9.