Feature: CSON support (#1305)

Adds CoffeeScript Object Notation CSON support in Web Essentials: https://github.com/bevry/cson

Following are the highlights:
* Content type.
* Used CoffeeScript icon.
* Menu items.
* Compilation.
  * CSON to JSON.
  * JSON to CSON.


**What's pending:**

Compile on Save: (also need settings to make it disable) so the CSON or JSON files which has their counterparts available should be in sync on save.