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
Again, you don't need all these dependencies if you just want to use the message types from another package.