Indicate in procline that manager have stopped
Do not stop heartbeat even when manager is already stopped

* Heartbeat should never stop (discussion: https://github.com/mperham/sidekiq/commit/ba8c8a57b962489333ce2cc01bdcc0aa381572b8#commitcomment-5996837)
* Test that heartbeat stores data in Redis with ttl
Switch to original proctitle better while testing
Merge pull request #1650 from theoldreader/procline

Heartbeat should never stop