PIM-3360 : remove deprecated base repository
PIM-3360 : use classic doctrine repository
PIM-3360 : re-work repositories to get ride of custom base entity repository
PIM-3360 : fix association type and attribute group repositories
PIM-3360 : fix a group repository call
PIM-3360 : notice BC Breaks in changelog
Merge pull request #1321 from akeneo/refactor/remove_deprecated_base_repository

PIM-3360 : remove deprecated base repository