Add support for sessions
This would be a real shot in the arm for jester and make it a much better web framework.  As far as I can tell, jester doesn't have support right now for something like sessions, such as PHP has: http://php.net/manual/en/session.examples.basic.php

Right now it looks like an interger/id field could be added in the `Request` object, and then sent to the user via the `cookies`.  There would probably need to be a table or something to record sessions.

The reason why this is important to add is so jester could have support for something like CSRF tokens.