PIM-3236 : add a category filter in PQB and use it in filter bundle
PIM-3236 : add specs for PQB category filter
PIM-3236 : add specs for category filter (filter bundle)
PIM-3236 : update changelog

Conflicts:
	CHANGELOG.md
Merge pull request #1703 from akeneo/PIM-3236

PIM-3236 : add a category filter in PQB
Fix style and phpdoc
Refactor SequentialEditController