PIM-2216 : update formatters
PIM-2216 : fix multiselect formatter, add notes to change log and
upgrade doc
PIM-2216 : move twig property (formatter)
PIM-2216 : add a dedicatd product groups formatter
PIM-2216 : uniformize metric and image properties (formatter)
Merge branch 'master' into mongo/formatters

Conflicts:
	CHANGELOG.md
PIM-2216 : update option formatter to be ORM/ODM compliant
PIM-2216 : update mongodb hydrator to be able to deal with option and
options hydration (from ORM storage)
PIM-2216 : update attribute option normalizer
Merge branch 'master' into mongo/formatters
PIM-2216 : date property doesnt depends anymore on Mongo, hydrator
convert to php date first
PIM-2216 : fix CS
Merge pull request #885 from akeneo/mongo/formatters

PIM-2216 : update formatters (MongoDB support)