Post preview

You can now preview posts from the list view. The link will only be available
when a post is not published, because why else would you preview something at this
point in time? Eventually I'd like it to be where you can preview something that
you haven't actually saved yet, but with posts it's probably alright to just let
you view unpublished posts and call it a feature!

Also torched readme and license.txt and added our own Readme!

@gholtslander