Revert "Convert exceptions into transmittable errors"

This reverts commit 5166722b799d6f442b08e46767cc89d326910c64. We are not
sure how this affects the inter-shop communication – so we skip this for
now, even this might make sense…
Moved category handling to dedicated service
Construct exception correctly
Enabled authorization for categories
Updated calls to category service
Do not enforce category revision ordering

Those will just be hashes – no ordering applied. AND this is already
handled by the replication source.