Add integration with VSTS

FYI @jess has spent a bunch of time integrations lately, and I think we can now semi-reasonably solve VSTS in the new React-powered components.

The thinking is now:

  • Add a provider to our vendored/forked/ripped apart version of django-social-auth
  • Add VSTS integration using the new React bits, which makes it a lot easier to build dynamic configurations

I will say it’s not a priority, but I might toy with it in my spare time.