metrics: add support for PCP#363

Merged

peterbourgon merged 10 commits intogo-kit:masterfrom

suyash:pcp-go-kit-pr

Oct 17, 2016

Commits on Sep 20, 2016

Commits on Oct 6, 2016

metrics/pcp: add unit to histogram
suyash
committed

Commits on Oct 13, 2016