HOTFIX: Include RocksDB dependency in release tarballs
HOTFIX: Include RocksDB dependency in release tarballs

Without this change `./gradlew releaseTarGz` (and its variants) will not include the RocksDB jar, which is required for Kafka Streams, in Kafka's `libs/` folder.  The impact is that any Streams job will fail when it runs against a broker that was installed via a release tarball.

guozhangwang junrao : please review.

Author: Michael G. Noll <michael@confluent.io>

Reviewers: Jun Rao <junrao@gmail.com>

Closes #1007 from miguno/trunk-rocksdb-fixes

Ishiihara/kafka,gf53520/kafka,ijuma/kafka,Chasego/kafka,noslowerdna/kafka,noslowerdna/kafka,apache/kafka,TiVo/kafka,themarkypantz/kafka,ErikKringen/kafka,TiVo/kafka,geeag/kafka,MyPureCloud/kafka,sslavic/kafka,Chasego/kafka,rhauch/kafka,rhauch/kafka,mihbor/kafka,KevinLiLu/kafka,airbnb/kafka,Chasego/kafka,Ishiihara/kafka,lindong28/kafka,eribeiro/kafka,apache/kafka,eribeiro/kafka,sslavic/kafka,gf53520/kafka,sebadiaz/kafka,geeag/kafka,noslowerdna/kafka,noslowerdna/kafka,Esquive/kafka,rhauch/kafka,themarkypantz/kafka,Ishiihara/kafka,eribeiro/kafka,MyPureCloud/kafka,themarkypantz/kafka,KevinLiLu/kafka,airbnb/kafka,airbnb/kafka,apache/kafka,mihbor/kafka,guozhangwang/kafka,guozhangwang/kafka,guozhangwang/kafka,lindong28/kafka,mihbor/kafka,lindong28/kafka,ijuma/kafka,airbnb/kafka,KevinLiLu/kafka,ollie314/kafka,ijuma/kafka,lindong28/kafka,sebadiaz/kafka,richhaase/kafka,themarkypantz/kafka,apache/kafka,ollie314/kafka,guozhangwang/kafka,eribeiro/kafka,geeag/kafka,ijuma/kafka,MyPureCloud/kafka,richhaase/kafka,Esquive/kafka,Ishiihara/kafka,ollie314/kafka,TiVo/kafka,gf53520/kafka,Chasego/kafka,ErikKringen/kafka,MyPureCloud/kafka,richhaase/kafka,Esquive/kafka,gf53520/kafka,TiVo/kafka,ErikKringen/kafka,ErikKringen/kafka,mihbor/kafka,rhauch/kafka,sebadiaz/kafka,ollie314/kafka,Esquive/kafka,sslavic/kafka,sebadiaz/kafka,geeag/kafka,KevinLiLu/kafka,richhaase/kafka,sslavic/kafka