munkitools2 recipe

- MunkitoolsURLProvider: support multiple 'latest' URLs, and
  stub support for Munki 2 release downloads
s/Update/Center/g
munkitools2.munki: Skip the custom processor, use autobuild URL.
NAME munkitools2.munki.recipe 'munkitools2'
Merge pull request #45 from autopkg/munkitools2

Munkitools2!