def new_image_markup(gallery)
      render_to_string(
        file: 'bootsy/images/_new',
        formats: [:html],
        locals: { gallery: gallery, image: gallery.images.new },
        layout: false
      )
    end
def new_image_markup(gallery)
      render_to_string(
        file: 'bootsy/images/_new',
        formats: [:html],
        locals: { gallery: gallery, image: gallery.images.new },
        layout: false
      )
    end
Private: Returns the String markup to render
 a form to upload a new image in a given gallery.

 gallery - The `Bootsy::ImageGallery` instance which
           the image will be uploaded to.