increase small graphs plotting speed by delaying html updates
increase small graphs plotting speed by delaying html updates

Chrome Dev Tools indicate that code that updates last values triggers
layout recomputations when we start to plot next graph. So we batch
text updates separately.

Change-Id: If92233e8193122176ce587d5127472eff8116ede
Reviewed-on: http://review.membase.org/4425
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Reviewed-by: Benjamin Young <399aded95f850edb83f13cae14dbe3e10ed19071@bigbluehat.com>

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