Automatic loading of all templates

This pull request makes TinyMCE load all available templates into editor. So user is only required to put html template file into /media/editors/tinymce/templates and refresh his browser window without creating any additional files or interfere into plug-in code.

Proper feature request has been created here: http://forge.joomla.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_id=8549&tracker_item_id=33954