UNDERTOW-272 Validate non canonical name for FileResource

I've added same validation used in master for 1.0.x branch.
Directories represented with symbolic links can be missed in 1.0.x without this validation.
Hi,
Thanks for comment.
I was reusing same validation from 1.1.x branch.
A case sensitive flag can be more appropiate, my first thought is that this flag can be defined at FileResourceManager() level in the constructor, as a boolean flag.
What do you think ?