Initial implementation

Would like to eventually be able to name the created authentication resource, but for now opted to have this hard coded for easier implementation details. When named authentication resources are needed, we should update the gem to support this functionality.

I also refactored the generators to simplify them, and took out the support for the existing check. Would also like to eventually move this functionality back over when we find need to upgrade an existing app to a newer version of this gem that requires migration updates.

Let me know any feedback you might have, tried to rebase but had issues :/. I'll eventually get better at rebasing.