Login: Need an easy way to logout

[PeteDuncanson]

Noticed when running the tests that if you are already logged in then it won't show the login form but redirect you to the Content section. This means that some of the tests are randomly failing.

Need to ensure we "logout" before we "login", suggest this is something we do as part of the login function in LoginPage so its always done. I'm wondering if we can't just run some script that will blitz the cookie in the browser and then go to the login url. That should do it...