Add a 'ReferenceEntity class name' in the nodes adminlist

It could be very usefull to display the "refered entity's name" of each node displayed in the AdminList (BACKOFFICE/en/admin/nodes/). I had some trouble with the entity manager not present in AbstractAdminListConfigurator, but here's a fast development to do it.

Also, it could be great to be able to filter and order the list on this new "refered entity's name" column. But I guess there's a missing property in NodeTranslation. Maybe a "publicVersionRefEntity" ?

Please tell me what do you think. Thank you very much.

Matthieu Cornut - http://www.liip.ch/en