Testing pre-commit hook

Hooks documentation

NB: This commit has a file (app/app.js) which will not pass lint to
test the pre-push hook.

Documenting hooks complete.

This commit fixes the lint error in app/app.js introduced before.

Added note about os x
Responding to reviews: clarify hooks, simplify sample hook.
Merge pull request #220 from makyo/develop

This is a docs only change.