FLUME-1716: Update CHANGELOG for rc3
FLUME-1716: Update CHANGELOG for rc3

(Brock Noland via Brock Noland)

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