FLUME-1747: Update CHANGELOG for flume 1.3.0 rc6 to include FLUME-1740
FLUME-1747: Update CHANGELOG for flume 1.3.0 rc6 to include FLUME-1740

(Brock Noland via Brock Noland)

iaiengxia/flume,tmgstevens/flume,tinawenqiao/flume,szaboferee/flume,tmgstevens/flume,iaiengxia/flume,szaboferee/flume,szaboferee/flume,iaiengxia/flume,tinawenqiao/flume,tmgstevens/flume,tmgstevens/flume,iaiengxia/flume,szaboferee/flume,tinawenqiao/flume,tinawenqiao/flume