Handlebars Compiler

Addition of a compiler for handlebars templates.

Defaults to in place, and version 1.3.0.
Yes there is an official NPM for this: https://www.npmjs.org/package/handlebars.

@henrycthomas, you can see the examples [here](https://github.com/madskristensen/WebEssentials2013/tree/2adf99c1e2c03a90d8a4969c285b0a8b726174f9/EditorExtensions/Resources/server/services) and in the C# code, you can find the corresponding compiler class (like `LessCompiler.cs` <-> `srv-less.js` and all the helpers are in place, just clone the code and make changes).