Revert "Refactor rule category field. It was calculated with the category paths and search tokens in the RuleFeed.  Moved this logic to the API."

This reverts commit d9b65b2902e6e4e919973b6cc4fa2b2b2b47029b.
Merge pull request #179 from gsegura/develop

Revert "Refactor rule category field due to some validation errors