Adding Actionlib

1. In simple language, the Action library is just a package of ROS which implements server-client interaction with the added advantage of getting a feedback at the very same time.
2. It is fairly easy to use and our code majorly depends on it.
3. When you install ROS, actionlib is directly installed in your system. It is just that you need to create a package in your catkin workspace.
4. To get started with actionlib and also to implement it, it is useful to got through the tutorials and summary are provided in the links here and here respectively.