Logic less array iteration

If `:to_s` is specified in the `:dictionary_access`, then the `this` keyword will return the `.to_s` value for the element under consideration.

Given

    { :article => ['Article 1', 'Article'] }

And

    - article
      tr: td = this

This will yield

    <tr>
      <td>Article 1</td>
    </>
    <tr>
      <td>Article 2</td>
    </tr>


An alternative approach would be to add a new option to the logic less mode to enable the `this` keyword for String elements.