Read profile images from Google OAuth correctly

Summary: Fixes T9972. Not sure if this was always a bug or the API changed. There's also a "url" we can use now.

Test Plan:
Refreshed a Google OAuth account link, got a profile picture:

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T9972

Differential Revision: https://secure.phabricator.com/D14753