[#1823] Fix play.exceptions.CompilationException

[lighthouse #1823](play.lighthouseapp.com/projects/57987/tickets/1823)
I think the problem is than, that the name of a directory must be cheched as well by its canonical name. My implementation was base on the assumption, that java packages must be allways lower case and i do not have to check the directory for case insensitivity. I will update my pull request.
You tested this with the normal "play run" on the small sample application from #786 1823 lighthouse ticket?