Vision devel

Vision was restructured into four parts:
* **vision_node:** receives images from the camera node and send robots poses and ball position to strategy
* **vision:** main class for vision, with run() method which apply computer vision algorithms to the received images
* **gui:** deals with showing images and mouse interaction
* **segmenter:** segments images (currently, only RGB frames) to generate masks that will be used to locate robots

Since the depth test video was buggy, only RGB is being used so far.