allow overriding follow_symlink on Train::File

[miah]

The File resource in InSpec the symlink related options isn't working right because follow_symlink is always true.

Consider..

module Train
  class File
    def initialize(backend, path, follow_symlink = true)
    end
  end
end

The remote file resources in train were not allowing this to be set.

Related inspec/inspec#3876

[chef-expeditor]

Hello miah! Thanks for the pull request!

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