fixed catkinization, compiles on hydro

Fixed a bit the catkinization, there were some issues:

- The download link for ARToolkit did not work properly
- Added dependencies on *_gencpp for waiting on message generation in ar_pose
- Added libraries on artoolkit and copy-target dependencies to make sure that ar_pose waits until artoolkit has finished compiling and copying the libraries.

I've tested it and it compiles fine under hydro
It is the official variable and it is available on hydro. The problem is that I tried to make this package compatible with ar_kinect which includes the header files from the artoolkit package as e.g.

    #include <AR/ar.h>

However if you do **INSTALL_COMMAND cp -r include/AR ${CATKIN_DEVEL_PREFIX}/${CATKIN_PACKAGE_INCLUDE_DESTINATION}** then the header files would be copied under *devel/include/artoolkit/AR/ar.h* instead of *devel/include/AR/ar.h* and thus the ar_kinect package is unable to find those headers.

I can revert this back if you want and modify the ar_kinect package instead...