Summary: Ref T1536. This gets the single queries out of the View and builds a propery Query class for ExternalAccount.
Test Plan: Linked/unlinked accounts, logged out, logged in.
Reviewers: chad, btrahan
Reviewed By: chad
CC: aran
Maniphest Tasks: T1536
Differential Revision: https://secure.phabricator.com/D6212
