[readme] add Steve Lum to contributor list, chef cookbook centos support
[readme] add Steve Lum to contributor list, chef cookbook centos support

pauloconnor/sensu,keymone/sensu,rbramwell/sensu,quodlibetor/sensu,crewton/sensu,sensu/sensu,npe9/sensu,somic/sensu,upfluence/sensu,bf4/sensu,cread/sensu,withnale/sensu,m4ce/sensu,miyakawataku/sensu,solarkennedy/sensu,Tapjoy/sensu-mirror,portertech/sensu,disqus/sensu,javrasya/sensu,zuazo-forks/sensu,roobert/sensu,yonglehou/sensu,disqus/sensu