Grunt build upgrades

Sorry about the large changeset. This upgrades the build and hopefully supports all of the scenarios we had in mind or at least makes them easier.

### Summary
* Code coverage only applies during CI builds
* CoffeeScript and JavaScript supported everywhere
* LESS and CSS Support
  * Using LESS  now (a lot more power/flexibility on CSS and supports plain CSS)
* Generate source maps for CoffeeScript and LESS
* Linting for LESS/CSS
* Latest versions of build dependencies
* Using locally installed grunt-cli and nw-gyp for Travis builds
* Simpler tasks semantics (IMHO)

### Known Issues
* Had to remove the nw-gyp task for Travis builds because node-midi fails to compile :(
  * Ideally we'll get this running again later as a sanity check even though it has no impact on tests.

### TODO
* Fix source maps for LESS
* Update the README on how to use the new build tasks
* Document each custom task in Gruntfile
* To latest Angular once this branch is merged into develop
This is a clone of Bootstrap's variables which we can now customize without having to make changes to Bootstrap directly. Basically we can theme Bootstrap now and not have to do overrides in our CSS.