Update default dublin core template (#657)

* Update default dublin core template

  Update the template to:
  - expand newline in the metadata to <br> tags
  - run it through filter_xss before displaying as is done in the
    metadata template.

* Updated based on feedback in pull request

theme/theme.inc

@@ -646,6 +646,7 @@ function islandora_preprocess_islandora_dublin_core_description(array &$variable
     }
   }
   $variables['dc_array'] = isset($dc_object) ? $dc_object->asArray() : array();
+  $variables['dc_array']['dc:description']['value'] = nl2br(filter_xss($variables['dc_array']['dc:description']['value']));
 }
 
 /**