Shedna/enable third party auth on studio

@talbs can you check for the buttons' style ?
@johncox-google if you wanna take an eye on this ?
cc @nedbat
For both the refactoring question and the dashboard question I think the thing to do now is talk to someone at edX. I'm not part of that organization, so I can't give you an authoritative answer on either front.

I can offer my opinion on the dashboard question, though: any system that solicits and stores user access grants from third party systems must have UX for revoking those grants. The LMS has this via the dashboard. It sounds like the CMS doesn't have a dashboard, so another solution is required.

To my mind this feature is a hard requirement because

a) not all third party systems are guaranteed to have this UX; and
b) users should not be required to go to a third party system to manage access grants in an edX deployment.

But that's just my opinion, and the edX folks could say more.