Remove "travis" in source code

python/src/main/java/org/apache/zeppelin/python/PythonUtils.java

@@ -70,8 +70,8 @@ public class PythonUtils {
   }
 
   public static String getLocalIP(Properties properties) {
-    // zeppelin.python.gatewayserver_address is only for unit test on travis.
-    // Because the FQDN would fail unit test on travis ci.
+    // zeppelin.python.gatewayserver_address is only for unit test.
+    // Because the FQDN would fail unit test.
     String gatewayserver_address =
         properties.getProperty("zeppelin.python.gatewayserver_address");
     if (gatewayserver_address != null) {

zeppelin-interpreter-integration/src/test/java/org/apache/zeppelin/integration/ZeppelinSparkClusterTest.java

@@ -68,7 +68,7 @@ public abstract class ZeppelinSparkClusterTest extends AbstractTestRestApi {
   public static final String SPARK_MASTER_PROPERTY_NAME = "spark.master";
 
   //This is for only run setupSparkInterpreter one time for each spark version, otherwise
-  //each test method will run setupSparkInterpreter which will cost a long time and may cause travis
+  //each test method will run setupSparkInterpreter which will cost a long time and may cause a
   //ci timeout.
   //TODO(zjffdu) remove this after we upgrade it to junit 4.13 (ZEPPELIN-3341)
   private static Set<String> verifiedSparkVersions = new HashSet<>();

zeppelin-plugins/launcher/k8s-standard/src/test/java/org/apache/zeppelin/interpreter/launcher/K8sStandardInterpreterLauncherTest.java

@@ -29,9 +29,7 @@ import org.junit.Before;
 import org.junit.Test;
 
 /**
- * In the future, test may use minikube on travis for end-to-end test
- * https://github.com/LiliC/travis-minikube
- * https://blog.travis-ci.com/2017-10-26-running-kubernetes-on-travis-ci-with-minikube
+ * In the future, test may use minikube for end-to-end test
  */
 public class K8sStandardInterpreterLauncherTest {
   @Before