Homepage design

Fixes exercism/website#6

This PR does the following:

* Sets up file structure for stylesheets: dependencies, base, and modules
* Styles for the home page (right now, just the root/welcome page)
* Tested in latest versions of Chrome, Firefox, and Safari; IE9+ (maybe we should discuss browser/device support?)

Still to do:

* The Get Started button should link to a login action
* Links not working in footer because I am still not sure if Emblem.js will allow you to mix HTML tags and raw text. The source of much fist shaking today.
* Responsive design -- got started on this, realized we were missing a couple of breakpoints in the design, but this shouldn't be too hard to address. Will get a second PR going.
* Testing on mobile devices -- need to get a testing environment set up at home.
* Apply these styles/structure to the other public-facing pages. Those should go a bit quicker now that there is a baseline style.

Tasty screenshots -- the header section:

![](http://cl.ly/image/230E063i003y/Screen%20Shot%202014-06-14%20at%205.03.26%20PM.png)

Tasty screenshots -- the features/try it section:

![](http://cl.ly/image/3F3Z0u3T0x3f/Screen%20Shot%202014-06-14%20at%205.03.38%20PM.png)