Implemented Logout and url using slug

I have now implemented the logout function, so the user can logout. On top of that I have implemented the usage of slugs in the url instead of ID. The ID is bad for SEO and it is less clean. To do that I first started out trying to make a simple version my self, since the slug needed to be unique in all cases. However, this turned out to be a bit more complex than I first thought. So when I found a unique slugify method I implemented it instead. It needs to be thoroughly tested, but from limited manual testing, it seems to work so far.