Revert "Merge pull request #11299 from arunagw/disable_implicit_join_references_removed"

`disable_implicit_join_references=` was only deprecated on `master`,
not with rails 4.0. We can remove it after 4.1

This reverts commit 3c719ead414ffd29e71efce185698af979052abb, reversing
changes made to d5c3bf9722abd5733a769c8d789de3f74dbfb92d.