Bug 1816: Leave cluster if we're shunned while down.
Bug 1816: Leave cluster if we're shunned while down.

This allows you to re-join a node that was failed while it was down.

Change-Id: I2402e7b1a60da245af0464f76c74223cfb03cd9a
Reviewed-on: http://review.northscale.com/2719
Reviewed-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>

membase/ns_server,nimishzynga/ns_server,ceejatec/ns_server,nimishzynga/ns_server,t3rm1n4l/ns_server,nimishzynga/ns_server,daverigby/ns_server,pavel-blagodov/ns_server,membase/ns_server,pavel-blagodov/ns_server,mschoch/ns_server,mschoch/ns_server,pavel-blagodov/ns_server,vzasade/ns_server,ceejatec/ns_server,daverigby/ns_server,vzasade/ns_server,membase/ns_server,mschoch/ns_server,membase/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,t3rm1n4l/ns_server,vzasade/ns_server,daverigby/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,membase/ns_server,ceejatec/ns_server,mschoch/ns_server,vzasade/ns_server,mschoch/ns_server,daverigby/ns_server,t3rm1n4l/ns_server,mschoch/ns_server,nimishzynga/ns_server,ceejatec/ns_server,t3rm1n4l/ns_server,daverigby/ns_server,ceejatec/ns_server,membase/ns_server,pavel-blagodov/ns_server