Add copyright and license info to top of code files.

I just realized that I can't easily include Navigator's LICENSE file with my project. My project is GPL, but my tests don't need to be.

Plopping the LICENSE file into the tests directory is unclear, so I've added a code comment to each of Navigator's code files that show the project, copyright, license and URL. I think that fulfills the license requirements.

Since this project wants people to copy its code files into their project, I think adding these code comments would be useful for everyone.