3.1.0 sass

3.1.0 Font-Awesome converted to .sass

Sass files are:

```
build/assets/font-awesome/sass
    config.rb
    sass/
      _main.sass
      ...
```

* Uses a Compass config.rb : 
    * `sudo apt-get install ruby && gem install compass`
    * http://compass-style.org/help/
* Underscore prefixed modules to prevent spam file creation
* Main font-awesome.sass will create itself in the `../css` directory
* Each icon is a mixin.
* Custom icons are definable, assuming you have the unicode reference for your desired glyph.
* Various other classes have also been made available as mixins.

```
@import font-awesome/sass/mixins

.my-thing-that-acts-like-an-icon
  +fontawesome
  +icon-github
  +icon-spin

.icon-valve-steam
  +fontawesome
  +icon("/roflmao")

```