PIM-1813 : rename product attribute
PIM-1813 : rename product attribute translation
PIM-1813 : rename product attribute validator
PIM-1813 : rename product attribute classes and references
PIM-1813 : rename product attribute classes and references
PIM-1813 : update fixtures context
Update changelog
Merge pull request #635 from akeneo/refactor/rename_product_attribute

[WIP] Refactor/rename product attribute