Please copy the spark-streaming-kafka-0-8_2.11-2.0.0.jar file into this directory. This is the co-ordinate for getting the jar file. 
"org.apache.spark" % "spark-streaming-kafka-0-8_2.11" % "2.0.0"

The following download link can be used to get the JAR file. 
http://search.maven.org/remotecontent?filepath=org/apache/spark/spark-streaming-kafka-0-8_2.11/2.0.0/spark-streaming-kafka-0-8_2.11-2.0.0.jar