PATCH: Add modalBackdrop opacity, color options to Drupal.settings.CToolsModal

Currently, the modalBackdrop color and opacity are hardcoded into modal.js, making it impossible to theme. I added those options to the Drupal.settings.CToolsModal object -- in line with how the closeText, closeImage, and throbber work. Here's the change:

    var opts = {
      // @todo this should be elsewhere.
      opacity: Drupal.settings.CToolsModal.backDropOpacity,
      background: Drupal.settings.CToolsModal.backDropColor
    };

...and then reflected in modal.inc

  $settings = array('CToolsModal' => array(
    'closeText' => t('Close Window'),
    'closeImage' => theme('image', ctools_image_path('icon-close-window.png'), t('Close window'), t('Close window')),
    'throbber' => theme('image', ctools_image_path('throbber.gif'), t('Loading...'), t('Loading')),
    'backDropOpacity' => '.55',
    'backDropColor' => '#fff'
  ));