Re-structuring project directories.
The whole point is that the meaning of "src/" differs for catkin and for ROS. Catkin requires all ROS packages to be inside a "src/" dir. Hence, I created an "unball/" dir inside "src/" to mark it as a ROS package. The whole UnBall ROS package is inside "src/unball/" now.
The new structure is

```
/
  hardware/
  firmware/
  software/
    src/
      CMakeLists.txt # symbolic link required by catkin
      unball/
        config/
        include/unball/
        launch/
        msg/
        scripts/
        src/unball/
        test/
        CMakeLists.txt
        package.xml
```

Using the structure recommended by [catkin](http://wiki.ros.org/catkin/workspaces) and [ROS](http://wiki.ros.org/Packages).

Closes issue #20.