worker: add pulsing
worker: use redis hash for scale
worker: remove pulse field on unregister
worker: pulse instantly to avoid pruning
worker/pulser: add test
worker: review stuff
worker: rename pulse to heartbeat and add to web
worker: remove redis call for scale
use iso8601 time
fix pruning workers without heartbeat
worker: pass heartbeat instead of hash
Merge pull request #1 from Sirupsen/pulse

worker: add pulsing