Updated authentication methods to login v2

@katowulf - Please review but **do not merge**. I want to get your thoughts on everything up to this point. There is still more work to be done here: testing (I am going to need to updated `mockfirebase` first...), removing Simple Login code, taking authentication out of this user management file, etc. Please provide any feedback on how things are structured though.
Should we bring this inline with the other services and allow it to be decorated/extended? Now is probably the last chance here.