Make .done() and .fail() callbacks on model.fetch() calls work as expected.

Summary:
Create a separate Deferred for App.oauth.ajax() and resolve that when the
resource request is resolved, NOT the token request

Test Plan:
- View an individual post (while logged out) and it loads without JS errors.
  Note this is only an issue when loading directly, not when you first click the link from a post list

Reviewers: shadowhand

Reviewed By: shadowhand

Differential Revision: https://phabricator.ushahidi.com/D142