Add Melodic build badge

Author: rhaschke

README.md

@@ -4,6 +4,6 @@ This package includes the ROS messages specific to MoveIt!
 
 ## Travis - Continuous Integration
 
-Indigo | Jade | Kinetic
------- | ---- | -------
-[![Build Status](https://travis-ci.org/ros-planning/moveit_msgs.svg?branch=indigo-devel)](https://travis-ci.org/ros-planning/moveit_msgs) | [![Build Status](https://travis-ci.org/ros-planning/moveit_msgs.svg?branch=jade-devel)](https://travis-ci.org/ros-planning/moveit_msgs) | [![Build Status](https://travis-ci.org/ros-planning/moveit_msgs.svg?branch=kinetic-devel)](https://travis-ci.org/ros-planning/moveit_msgs)
+Indigo | Kinetic | Melodic
+------ | ------- | -------
+[![Build Status](https://travis-ci.org/ros-planning/moveit_msgs.svg?branch=indigo-devel)](https://travis-ci.org/ros-planning/moveit_msgs) | [![Build Status](https://travis-ci.org/ros-planning/moveit_msgs.svg?branch=kinetic-devel)](https://travis-ci.org/ros-planning/moveit_msgs) | [![Build Status](https://travis-ci.org/ros-planning/moveit_msgs.svg?branch=melodic-devel)](https://travis-ci.org/ros-planning/moveit_msgs)