Refactor — 2.0

So this is a huge pull request. Sorry about that. It's a complete refactor.

First off, the cookie parsing/setting is abstracted away and left out of the module. This makes it easier to incorporate it into different frameworks etc. It also makes it so that we don't have to parse cookies in several places.

Did a bit of work on how sessions are created etc. This is basically some of the groundwork needed to add login on the node side.

The code is no using the strict mode.

100% test coverage has been added.

Did a bit of optimization on the way saving sessions work. There's now a default mode where a session is not persisted until explicitly told to. `autoSave` can be enabled to trigger a save every time the session is saved.

Also, readability (Sorry @ptte ;) ) and comments have been improved!

README to be updated.