PIM-3101 : introduce a product value normalizer
PIM-3101 : update product normalizer spec
PIM-3101 : add a spec for flat product value normalizer
PIM-3101 : update specs to deal with array and collection normalization
PIM-3101 : remove deprecated unit test (has been replaced by specs)
PIM-3101 : cleanup
Merge pull request #1389 from akeneo/PIM-3101-flat-product-value-normalizer

PIM-3101 : introduce a flat product value normalizer
PIM-3070: Remove useless files
PIM-3070: Remove dir content and task option
PIM-3070: Remove import/export directories from requirements
PIM-3070: Clean directories
PIM-3070: Update CHANGELOG.md