AMBARI-2368. Fix to remove user from host_component/actual_configs. (ncole)

git-svn-id: https://svn.apache.org/repos/asf/incubator/ambari/trunk@1492387 13f79535-47bb-0310-9956-ffa450edef68

ambari-server/src/main/java/org/apache/ambari/server/state/DesiredConfig.java

@@ -81,6 +81,7 @@ public class DesiredConfig {
   /**
    * Gets the user that set the desired config.
    */
+  @JsonSerialize(include = Inclusion.NON_EMPTY)
   public String getUser() {
     return user;
   }