Updates much of the layout

Controllers no longer use render when redirect would work (except user for now).
The flash is used to pass messages between requests, and forms have been changed
accordingly to display them.

Header and nav bar have their own css files now.

The nav bar (parent_bar partial) changed to have more logical flow. A wrapper
the width of the sidebar sits on the left, and two link tabs float left and
right within it. The wrapper pushes the item/parent thumbnail tabs to their
proper locations.

The header also is now starting to be properly arranged.