added medium and small format layouts
updated readme to add cross-browser compatibility requirement
Merge branch 'master' of https://github.com/devleague/Layout_1 into devleague
refactored large layout
added small layout with open nav
finished draft of medium layout
Merge branch 'master' of https://github.com/devleague/Layout_1 into devleague
pulled from remote
completed draft all 3 layouts
cleaned up css file