Initiate basic login at login screen

[vbrown608]

Currently, users accessing the site through basic auth are logged in automatically.

In the future, we may want to allow them to log in via basic auth by clicking a link on the login screen (similar to "authenticate with google"). This would provide more flexibility, for example allowing users to share a laptop if someone is without theirs.

[TheNotary]

This sounds great. It's possible to write a cookie to the user's machine too... so if someone actually clicks the logout buttom, bam they get the "logged out" cookie, and conditionally we can prevent the autologin stuff from taking place if the cookie is found on subsequent requests. Also, prevent the code from running for users who are already logged in. and upon successful login, we can delete this cookie off the client machine.