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
You're right, I'll push a commit fixing this