Ben Leggett

Also threw up https://github.com/containernetworking/cni/pull/1081 based on some of the discuss here, as a start.

> Looks basically good, but please split in to 3-or-so commits (spec changes, go renames, and implementation). Thanks! Yep, had it like that at one point. Fixed up, ty!

I'll resync this once #1090 + #1097 is in

Resynced - since this already adds a type alias (NetConf -> PluginConf) it replaces some of #1097 (but continues to follow the same basic approach).

@squeed @s1061123 PTAL - should be good from my perspective to merge when you wish.