http://wiki.ros.org/ROS/Tutorials/WritingPublisherSubscriber%28c%2B%2B%29#roscpp_tutorials.2BAC8-Tutorials.2BAC8-WritingPublisherSubscriber.Building_your_nodes-1

addmessagefiles, addservicefiles, and generate_messages are not necessary for publisher/subscriber in cmakelist. Not to mention the appearance of AddTwoInts.srv... this whole page is about talk/listener. This must be messed up with the service/client version of cmakelist.