Contribute: Visual refresh, tie to Hello

Refresh the view on the Contribute page to
match those of the Hello and Edit pages,
albeit in a bit of a threadbare manner.

Also make it so the 'contribute' button
on the Hello page works.
Contribute: Show log-in or log-out links

Show the links for logging in or out at
more-appropriate times.

We probably want a session management
piece in place, now.
Change dependency on Express to 3.1

We were using Express 3.0 rc4; let's use
the most recent version of 3.1.
Refactor: Put controllers in own files