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

[sigma at smx.pair.com]

> I'm fairly certain that almost everyone has been operating under this
> assumption, whether warranted or not.  Particularly as there exists an
> optional abuse contact, if one isn't provided, the tech contact seems like
> an implicit fallback.  The other assumption, that the netblock owner does
> not wish to be contacted regarding abuse, seems intractable.

Replying to myself, I would like to say that Dillon-San's suggestion was
much better - to fallback on the tech contact but at a very low volume so
you're more likely to be received kindly.

Kevin