[GH-521] DDC-2161 Added failing test that moves a foreign key

This issue is created automatically through a Github pull request on behalf of alex88:

Url: https://github.com/doctrine/doctrine2/pull/521

Message:

I'm including a test that should pass once the DCC-2161 is fixed.

As I'm stating in the bug, when you create an entity with a self-referencing bidirectional oneToMany, then you create another entity and move the oneToMany to that entity, changing the targetEntity in the ManyToOne, doing a schema:update doesn't move the foreign key reference inside the Mysql table.