~ avoid duplicate #whenStop calls
~ separate spontaneous 'disconnect' & preemptive 'dismiss' (it caused master to receive 'cluster' native 'disconnect' event)
~ worker#beforeStop to stop server not app
~ 'close' is triggered by worker#disconnect from cluster, no need to double the effort
refactor after split emitter,status,cache
bugfix of cache start
Merge pull request #76 from inexplicable/cluster3

Cluster3