Remove deprecated `::File.exists?` Using `::File.exist?` instead.

Also fixed bug with symlinks what was checked the using `exists?` and `exist?` at same time, but in specs was mocked only `exists?`
@lamont-granquist I don't know how it must be working. How to decide right way? It must set owner and group or not? I suppose what you as a core team member must know this better.