Add User Authentication

[mbramson]

Doesn't have to be super fancy or secure, but it would be nice to get something in place so that a current user can be put in session for other functionality down the line such as groups, admin, etc.

[ericworkman]

https://github.com/ueberauth/ueberauth is pretty straightforward to add, aside from the application auth tokens and what not if we want to do Twitter or Google etc auth.