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?`
Well first thing is, can you validate that I transformed your set_all! function correctly here, and use this instead:

``` ruby
    # Modifies @current_resource, setting the current access control state.
    def set_all!
      if ::File.exist?(new_resource.path) &&
        new_resource.is_a?(::Chef::Resource::Link) &&
        !current_resource.link_type == :symbolic
          set_all
        end
    end
```