gabriel.achille's sandbox: a11y form

This module fixes some accessibility errors in form rendered by Drupal API
and Webform module. It includes:

• Drupal core Form API:
  • fieldset: set the label to invisible instead of none when "Hide label" is ticked.
  • Replace the * by (required) for required field. DISABLED
  • add a field formatter for image that remove the alt text (necessary for certain
    decorative use of image)
  • file : Add the accessible attribute aria-live to the dynamically updated region
    where error message get displayed. (in case of wrong file type)
• Poll module: remove unnecessary label tag wrapping the radios input
• Webform:
  • fieldset: set the label to invisible instead of none when "Hide label" is ticked and Replace fieldset element by a heading (optional).
  • for multiple-elements (radios, checkboxes, select_or_other, managed_file) :
    replace <div><label for="blabla">MY TITLE</label>...
    by <fieldset><legend><span>MY TITLE</span></legend>...
  • select_or_other:
    • attach the title to the wrapper element instead to the radios/checkbox/list element.
    • remove the action change focus JS action when option other is selected.
  • file_managed: add a title attribute to the upload input element
  • webform_time: add hidden label to hour and to minute input.
• date_views: remove duplicate id and fix orphan label for date_popup exposed view filter.