FLUME-2551. Add dev-support directory to source tarball.
FLUME-2548: Enable SSLv2Hello for Avro Source and NettyAvroRpcClient

(Hari Shreedharan via Jarek Jarcec Cecho)
FLUME-2549: Enable SSLv2Hello for HttpSource

(Hari Shreedharan via Jarek Jarcec Cecho)
Update pom.xml files to version 1.5.2
Update docs to 1.5.2
Update RELEASE-NOTES for 1.5.2
Update CHANGELOG for 1.5.2