Exclude kafka server by default

It could be excluded in the bus starter, but no harm in doing
it here for 1.2.0

pom.xml

@@ -115,6 +115,16 @@
 				<type>pom</type>
 				<scope>import</scope>
 			</dependency>
+			<dependency>
+				<groupId>org.springframework.cloud</groupId>
+				<artifactId>spring-cloud-starter-stream-kafka</artifactId>
+				<exclusions>
+					<exclusion>
+						<groupId>org.apache.kafka</groupId>
+						<artifactId>kafka_2.11</artifactId>
+					</exclusion>
+				</exclusions>
+			</dependency>
 		</dependencies>
 	</dependencyManagement>
 </project>