[#30192] Disallow directory listings in default config

This is a continuation of [JoomlaCode item 30192](http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=30192) and modifies the distributed `htaccess.txt` and `web.config.txt` files to disallow directory listings by default.
Can you change this to Joomla 3.4 as it reads better than just 3.4
Also if you create a stub file on the wiki now then this can be commityed with the correct link - we both know it will be forgotten about otherwise