UNDERTOW-275 Support Follow Symlinks

Proposal for "Follow Symlinks" feature.
Added more tests to cover possible scenarios.
Please, feel free to review it or comment possible missing scenarios.
This should stop checking at the root of the resource manager. e.g. if the resource managers base is /opt/data/files it should not reject a path if /opt/data is a symlink, only if there is a symlink inside /opt/data/files.