Added more hotkeys, updated some descriptions

Added most of the hotkeys in [composer_controller.js](http://www.codecademy.com/assets/dist/controllers/composer_controller.js) (~line 20,000 of the [jsbeautified version](https://gist.github.com/JoahG/8246112)). Some of the previous descriptions were found to be inaccurate compared to the name of the hotkey combo. 

Some key combos were excluded as they aren't presently working
`ctrl + ,` for menu, the macro recording keys `ctrl + alt+ e` and `ctrl +shift + e`, a few others I can't remember.