Mongodb/pim 1557

WIP Do not merge

Bug fix: [no]
Feature addition: [no]
Backwards compatibility break: [yes] : Relationship between category and product removed
Unit test passes: [no]
Behat scenarios passes: [yes]
Checkstyle issues: [yes]
ChangeLog updated: [yes]
Documentation PR: [NA]
Fixes the following jira: PIM-1557