[WIP] Create the right indexes in MongoDB
Fixes PMD var length
Add index purge
Fixes collection usage
Refactoring into smaller more centric class
Fixes reference access on function return
New specs and cleanup on the Listener
Merge branch 'master' into ensure_mongodb_indexes

Conflicts:
	CHANGELOG.md
Update CHANGELOG.md
Use Locale and Currency repo getActivated methods
Merge branch 'ensure_mongodb_indexes' of github.com:akeneo/pim-community-dev into ensure_mongodb_indexes
Runs through the @fitn fixer
Merge branch 'master' into ensure_mongodb_indexes
Merge pull request #1159 from akeneo/ensure_mongodb_indexes

Automatically create and purge indexes in MongoDB