ensure minimal size of arcs on bucket readiness pie chart
ensure minimal size of arcs on bucket readiness pie chart

Based of work of Benjamin Young.

We increase sizes of too small args at the 'expense' of largest
arc. With only 3 arcs max it seems acceptable approach, even though
it's not entirely cleanest.

Change-Id: I8fb19175c0557e7d6f1583c6edaa9752365a7676
Reviewed-on: http://review.membase.org/6611
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Reviewed-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>

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