Change some multis which just do reads to be pipelined for fasbetter perf.
Rewrite ProcessSet#each to use pipelining to avoid lots of roundtrips in large Sidekiq installations.
Use mget in History instead of making many roundtrips.
Pipeline queue lengths.
Use mset instead of a loop over set for Stats#reset.
Merge pull request #1588 from mperham/feature/pipelines

Feature/pipelines