Copy behavoir handling of Page class more precise. 

Hi

I saw your fork, and it solved one of my problems with the origin project.

I made some small changes, 
1. Rename class, so it work for me with the wolfcms version 0.7.5-SP1, I'm not sure if this is correct, but that was the only way it worked for me.
2. I changed the handling of sub-pages so that it reflects the code from Page::findByUri better. 

I hope you see value in these changes and also will create a pull request to the original project, as it is the one which is linked from the wolf plugin repo.

Cheers emanuel