Change third party auth login failure code to a 401, to detect authentication
success with no linked account.
If already authenticated, redirect immediately to the dashboard.
Use "Location" header correctly for 302 redirects from student views.
Add utility functions for simulating a running third-party auth pipeline.
Add a utility function for checking whether third party auth is enabled.
Respect default values sent by the server
Add Python APIs for account/profile information to user_api
Updating profile page to have social linking
Authors: Renzo Lucioni, Alasdair Swan, Stephen Sanchez, Will Daly
