New Behat tests on grid completeness

Conflicts:
	features/product/completeness.feature
Fixes too many flush from versionning and PIM-2916

Conflicts:
	CHANGELOG.md
	src/Pim/Bundle/VersioningBundle/EventListener/MongoDBODM/AddProductVersionListener.php
CS Fixes
Fixes phpDoc and function visibility
Remove non wanted changes from cherry-pick
Merge pull request #1270 from akeneo/1.1_backports_PIM-2916

1.1 backports pim 2916