improve menu transitions.

this code needs to grow into an API for writing code that controls this
kind of UI behavior.
reduce width of 'menu'
css tweaks: force body to full viewport height, add padding to menu's list, give entire body padding. padding in #controls area is independent of this. hope to find elegant solution that'll keep these paired.
give #controls a base color to keep main content area from bleeding under it
Merge pull request #4 from twinlabs/menu-improve-transitions

improve menu transition behavior