CoffeeScript: Rewired compilation with Node.js

Following the node-based [command-line documentation](http://maxtaco.github.io/coffee-script/) for CoffeeScript, now our compiler is wired with NodeJs.

Except for the `StandardError`, its working. I have tested the error messages on shell. The stdOut get the messages in this form:

```bash
C:\Users\Adeel\Desktop\test\ExampleProject\app.coffee:22:60: error: reserved word "public"
app.use require("stylus").middleware(path.join(__dirname, "public"))
```

The regex to parse this is [in place](https://github.com/am11/WebEssentials2013/blob/master/EditorExtensions/Margin/CoffeeScriptCompiler.cs#L12) to parse the error messages and [seed it to the `CompilerError` initializer](https://github.com/am11/WebEssentials2013/blob/master/EditorExtensions/Margin/CoffeeScriptCompiler.cs#L66-L82). The only problem is, the Process is not redirecting (handing over) error output to `StandardError` (it captures only `\r\n`). 

@gcastre, perhaps you have some insights about the async error handling with lamdas? I used the same structure as you implemented for LESS compiler.

@SLaks, would it make sense to extract out the commonalities from margin, compiler and project-compiler classes of LESS and CoffeeScript?