Notification cleanup.
Notification cleanup.

Remove unused change handlers in notifications for backdoor and exploit
attributes and add headers for new Backdoor and Exploit TLOs.

cfossace/crits,0x3a/crits,korrosivesec/crits,lakiw/cripts,0x3a/crits,jhuapl-marti/marti,ckane/crits,dreardon/crits,ckane/crits,korrosivesec/crits,blaquee/crits,jinverar/crits,cfossace/crits,Lambdanaut/crits,kaoscoach/crits,Lambdanaut/crits,Lambdanaut/crits,cdorer/crits,korrosivesec/crits,DukeOfHazard/crits,DukeOfHazard/crits,ckane/crits,lakiw/cripts,blaquee/crits,cdorer/crits,jinverar/crits,Magicked/crits,cfossace/crits,Magicked/crits,lakiw/cripts,dreardon/crits,jinverar/crits,Magicked/crits,DukeOfHazard/crits,blaquee/crits,dreardon/crits,HardlyHaki/crits,ckane/crits,HardlyHaki/crits,DukeOfHazard/crits,jhuapl-marti/marti,HardlyHaki/crits,cdorer/crits,cfossace/crits,dreardon/crits,jinverar/crits,Lambdanaut/crits,blaquee/crits,jhuapl-marti/marti,Magicked/crits,lakiw/cripts,cdorer/crits,HardlyHaki/crits,0x3a/crits,kaoscoach/crits,jhuapl-marti/marti,korrosivesec/crits,0x3a/crits,kaoscoach/crits,kaoscoach/crits