Add dynamic reconfigure support for individual markers detection

Sorry, I only did for individual markers, what is the only part I used.

My code is ros-formatted by eclipse, so maybe is a bit mesh up with tabs/spaces. I will be happy to pull request a fully ros-formatted code if you want.

The enable/disable switch subscribes/unsubscribes to camera topic, what at the same time stops the CPU-hungry depth image to pointcloud nodelet. When not subscribed, the lazy publishing of the pointcloud makes a huge saving on CPU.