Can we add a session.delete(:key) method to sessions to make it behave more like a regular hash? There is currently a session.delete method, but that receives no arguments and just empties the session. It'd be easy enough to just add an optional argument and delete a key from the data hash if a key is provided, or empty the session otherwise. Although that could be a little volatile, we wouldn't want to have a key passed accidentally == nil, and end up emptying the session. Could the method naming be more clear? I propose session.clear! to clear out the session, session.delete(:key) for the normal hash operation.
