Update Kafka download version

Fixes #295

Author: robbavey

kafka_test_setup.sh

@@ -5,7 +5,7 @@ set -ex
 if [ -n "${KAFKA_VERSION+1}" ]; then
   echo "KAFKA_VERSION is $KAFKA_VERSION"
 else
-   KAFKA_VERSION=0.10.2.1
+   KAFKA_VERSION=2.0.1
 fi
 
 export _JAVA_OPTIONS="-Djava.net.preferIPv4Stack=true"