Lay the foundations for handling SSO with external applications

[carrollgt91]

We'll need to extend the user model to store the credentials for each new SSO provider.
We'll need to ensure we're creating a session for the user after the SSO has occurred.
We'll need to integrate this with the client application.
Ideally, we'll lay foundations that will make it easier to extend the application to include additional SSO providers.

We'll treat querying data from each SSO provider as a separate task.

[FarrandTom]

I'll begin working to setup the initial login form and signup form for users. Integrating that with the Front end seems straight forward enough, and that should extend the Users model with most of the correct functionality to add 3rd party SSO orgs shortly after.