update CHANGELOG for rc2 release
update CHANGELOG for rc2 release

titilambert/kapacitor,sputnik13/kapacitor,influxdb/kapacitor,influxdata/kapacitor,titilambert/kapacitor,yosiat/kapacitor,influxdata/kapacitor,bbczeuz/kapacitor,yosiat/kapacitor,bbczeuz/kapacitor,sputnik13/kapacitor,influxdb/kapacitor,sputnik13/kapacitor,bbczeuz/kapacitor,titilambert/kapacitor,influxdb/kapacitor,muxinc/kapacitor,adityacs/kapacitor,muxinc/kapacitor,yosiat/kapacitor,influxdata/kapacitor,muxinc/kapacitor,adityacs/kapacitor,adityacs/kapacitor