Add v2 heartbeat data.

This should break history so old over-common data isn’t clouding up
coronet stats.
Snag the core and php branch as well.

This will combine all the point releases into a single stat for more
readable detail.
Break generate stats array into a new fn
Call Jetpack statically
Add the anonymized IP octets to the stat.
Merge pull request #465 from Automattic/new-heartbeat-stat

New heartbeat stat