Feature: middleman angular setup

This adds the bare bones middleman setup with [Bourbon](http://bourbon.io/) and [Neat](http://neat.bourbon.io/) for the styles and grid system. Additionally it includes the latest version of angular via [Bower](http://bower.io/) (its a simple front-end package manager). 

The [middleman-angular-templates](git@github.com:damrbaby/middleman-angular-templates.git) gem makes it possible that we can define angular templates within separate files and have them inlined into the main html automatically, resulting in less server requests (pre-compilation).

[ngmin](middleman-ngmin) enables us to write the simpler angular injection notation with plain variable names like `$http` instead of having to use the clumsy array syntax `["$http", (http) -> ]`. Normally this is necessary because Javascript minifiers also change the names of "local" variables inside functions to the shortest possible  versions to save bytes. This wouldn't work with angular, because `$http` has meaning -> it tells angular to inject the http service as this argument.
This doesn't seem to be right. I figure it should be `bundle exec middleman`, shouldn't it?