PIM-1616 : add metric model to catalog bundle
PIM-1616 : add metric orm mapping
PIM-1616 : add metric mongodb mapping
PIM-1616 : change product value orm mapping to use catalog metric
PIM-1616 : update product value mongodb mapping to use metric model
PIM-1616 : update changelog
PIM-1616 : update deprecated references to flexible metric
PIM-1616 : move subscriber that converts metric from flexible to
catalog
PIM-1616 : move subscriber
Merge branch 'master' into refactor/metric_mapping
Merge pull request #582 from akeneo/refactor/metric_mapping

[WIP] refactor metric mapping ro support ORM / Mongodb ODM