CoffeeScript: Rewired compilation with Node.js.

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\ExampleProject\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#L16) to parse the error messages and [seed it to the `CompilerError` initializer](https://github.com/am11/WebEssentials2013/blob/master/EditorExtensions/Margin/CoffeeScriptCompiler.cs#L110-L126). The only problem is, the Process is not redirecting (handing over) shell output on `StandardError`. 

@gcastre, perhaps you have some insights about the async error handling with lamdas? I used the same structure as you implemented for LESS compiler.