MB-100 Remove dirty item age assertion in the flusher's loop.
MB-100 Remove dirty item age assertion in the flusher's loop.

If there are any issues in persisting dirty items into disk, a
more reliable way to deal with this issue is to remove the node
from the cluster instead of assertion crash.

Change-Id: I7901bce17937242dfbde63464355e3e1b937c7b0
Reviewed-on: http://review.couchbase.org/19174
Reviewed-by: Michael Wiederhold <a17fed27eaa842282862ff7c1b9c8395a26ac320@couchbase.com>
Tested-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>

daverigby/ep-engine,couchbase/ep-engine,abhinavdangeti/ep-engine,daverigby/kv_engine,daverigby/kv_engine,sriganes/ep-engine,sriganes/ep-engine,jimwwalker/ep-engine,couchbase/ep-engine,hisundar/ep-engine,couchbase/ep-engine,abhinavdangeti/ep-engine,daverigby/kv_engine,couchbase/ep-engine,abhinavdangeti/ep-engine,membase/ep-engine,jimwwalker/ep-engine,daverigby/ep-engine,owendCB/ep-engine,abhinavdangeti/ep-engine,abhinavdangeti/ep-engine,teligent-ru/ep-engine,teligent-ru/ep-engine,owendCB/ep-engine,teligent-ru/ep-engine,membase/ep-engine,hisundar/ep-engine,owendCB/ep-engine,hisundar/ep-engine,membase/ep-engine,jimwwalker/ep-engine,owendCB/ep-engine,membase/ep-engine,teligent-ru/ep-engine,daverigby/kv_engine,sriganes/ep-engine,daverigby/ep-engine,hisundar/ep-engine,sriganes/ep-engine,daverigby/ep-engine,jimwwalker/ep-engine