Add generator-mocha as peerDepedency

Fix #38
Improve CoffeeScript support

Additions
- New folder for CoffeeScript related files
- Make grunt-neuter play nicely with CoffeeScript
Fix app/index.js so it passes jshint tests
Make grunt-neuter run after all concurrent tasks.
Make prompt display CoffeeScript as default.
Adhere to coding standards :smile:
Move CoffeeScript option from prompt to a flag.