PIM-2919 : re-organize catalog subscribers
PIM-2919 : rename old catalog listeners
PIM-2919 : update change log
Merge branch 'master' into refactor/catalog_event_subscribers

Conflicts:
	CHANGELOG.md
PIM-2919 : update spec namespace
Merge pull request #1322 from akeneo/refactor/catalog_event_subscribers

Refactor/catalog event subscribers
PIM-3005 : fix the translation key of CsvWriter (used when a warning
occurs)
Merge pull request #1323 from akeneo/PIM-3005

PIM-3005 : fix the translation key of CsvWriter
PIM-3014 Prevent copying media without associated file