Fix media_wysiwyg.paragraph_fix_filter tests, which are failing in PHP 5.3

In modules/media_wysiwyg/tests/media_wysiwyg.paragraph_fix_filter.test there are many calls to preg_match_all(), which prior to 5.4 required a 3rd parameter, $matches. In order to run these tests in PHP 5.3, we'll need to refactor that file to pass 3 parameters.