handle already_balanced response from rebalance as ok
handle already_balanced response from rebalance as ok

Change-Id: Ib24a2b5b9a965e3a1ed7a30f622cc2cf672348ed
Reviewed-on: http://review.northscale.com:8080/795
Reviewed-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>
Tested-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>

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