README: add release token

Author: TSC21

README.md

@@ -1,7 +1,6 @@
 MAVROS
 ======
-
-[![Gitter](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/mavlink/mavros?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)  [![Build Status](https://travis-ci.org/mavlink/mavros.svg?branch=master)](https://travis-ci.org/mavlink/mavros)
+![GitHub release (latest by date)](https://img.shields.io/github/v/release/mavlink/mavros)  [![Gitter](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/mavlink/mavros?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 
 MAVLink extendable communication node for ROS.
 
@@ -68,9 +67,8 @@ CI Statuses
 -----------
 
   - ROS Kinetic: [![Build Status](http://build.ros.org/buildStatus/icon?job=Kdev__mavros__ubuntu_xenial_amd64)](http://build.ros.org/job/Kdev__mavros__ubuntu_xenial_amd64/)
-  - ROS Lunar: [![Build Status](http://build.ros.org/buildStatus/icon?job=Ldev__mavros__ubuntu_xenial_amd64)](http://build.ros.org/job/Ldev__mavros__ubuntu_xenial_amd64/)
   - ROS Melodic: [![Build Status](http://build.ros.org/buildStatus/icon?job=Mdev__mavros__ubuntu_bionic_amd64)](http://build.ros.org/job/Mdev__mavros__ubuntu_bionic_amd64/)
-  - Travis master: [![travis status](https://travis-ci.org/mavlink/mavros.svg?branch=master)](https://travis-ci.org/mavlink/mavros)
+  - Travis master: [![Travis Status](https://travis-ci.org/mavlink/mavros.svg?branch=master)](https://travis-ci.org/mavlink/mavros)
 
 
 [mrrm]: https://github.com/mavlink/mavros/blob/master/mavros/README.md