Login saml features

[nickbristow]

This branch is intended to be a work in progress based on @jessieay's work.

In the branch

• Adds login button on homepage
  • Only allows you to login with login.gov after account has been
  • Informs user they must sign in with github and add login first
• Adds button in profile to add Login.gov account to your existing account
  • Checks the user doesn't have an account
  • Checks that no other user is associated with the login account
• Adds button that allows you to remove login.gov from their account

Needed?

• Review/Refactoring
• Make this feature admin only?
• Design work
  • Placement of login
  • Only show login.gov button to admins?
  • not sure thats possible???
• Only allow admins to add login.gov to their account
• Create account with just login and not github??

[nickbristow]