[ppml] Proposal: make Abuse Handle *REQUIRED* for AS Registration

There are definite cases where using AS contact info for directing
abuse/securty issues is NOT appropriate.

Case in point:

These jokers had their own AS # and were probably the biggest source of open
proxy scans for this year...once I ultimately figured that out we started
going to their upstream AS's to get them yanked.

Fortunately these situations are relatively rare.

--Lawrence Baldwin