Updates layout and re-arranges content.
Updates layout and re-arranges content.

Only a small amount of material design from the google spec has been
added. Just enough to get us a layout and typography/color rules to
iterate on the documentation. There is still quite a bit of CSS work left
(mobile, cross browser compat).

This change also updates the content and site structure to better reflect
the design document.

Change-Id: Ica1163973fc3df464f2fbf42933f3141ce895ba7

vanadium/playground,vanadium/playground,vanadium/playground,vanadium/playground