Fixes #3 (USI) - Added blacklist protection around devices
Fixes #3 (USI) - Added blacklist protection around devices

When the delete handler was refactored the blacklist check was
removed. It has been readded. Any blacklisted devices will be skipped
for both delete and reassign if the user doesn't have the proper
permissions. Currently only full admins can manage the blacklist.

usi-lfkeitel/packet-guardian,packet-guardian/packet-guardian,packet-guardian/packet-guardian,packet-guardian/packet-guardian,packet-guardian/packet-guardian,usi-lfkeitel/packet-guardian,packet-guardian/packet-guardian,usi-lfkeitel/packet-guardian