Remove deprecated FlexibleEntityBundle
Remove deprecated methods
Replace FlexibleConfigurationException by LogicException
Remove deprecated spec
Fix SortersConfiguratorSpec
Fix ChoiceFilterSpec
Fix AddProductValueFieldSubscriberTest
Replace the use of flexible_class and flexible_value_class by
product_class and product_value_class
Update product manager and related spec to fix flexible entity removal
Update changelog and upgrade.md
Replace the use of deprecated createFlexibleValue by createProductValue
Replace the use of deprecated getFlexibleRepository by getProductRepository
Merge pull request #1028 from akeneo/deprecated/remove_flexible_entity

[WIP] Deprecated/remove flexible entity