Add single sign-on authentication.

[revalo]

• Adds Single Sign On to Quill.
• Also has the make admin button commits.

Summary of Single Sign On Flow is:

1. Click 'Sign In with Quill' which goes to my.hackmit.org/login?sso=https://mysite.com/login
2. Once user logs in, client side angular code hits /auth/sso with current user JWT and redirect url.
3. /auth/sso returns a 30 second SSO Token and redirects to https://mysite.com/login?token=ssoToken
4. https://mysite.com/login verifies timestamp and token signature and hits /auth/sso/exchange with the token to get all the user details.