Make Oauth-registration flows a bit more resilient to failures from the providers
Summary: basically by validating we have good user data when we set the user data.
Test Plan: simulated a failure from a phabricator on phabricator oauth scenario. viewed ui that correctly told me there was an error with the provider and to try again.
Reviewers: epriestley
Reviewed By: epriestley
CC: aran, Koolvin
Maniphest Tasks: T1077
Differential Revision: https://secure.phabricator.com/D2337