Requirejs Support 

Added Requirejs support
*  added the prompt for requirejs
* All sub-generators(Model/Collection/Router?view) updated to scaffold for requirejs.
* The sub-generator will look for **require.config** in main.js to check whether a requirejs app or not.
* Added tests for requirejs support
* Added a bootstrap.js with all bootstrap plugins (taken from generator-webapp)
* **Coffeescript** is not currently supported with requirejs. (will work on it).