CRM-9725 KCFinder file management issues on Joomla 1.7.x

No image upload /management seems possible with the new KCFinder integration with CKeditor/TinyMCE.
Had a go at debugging but I am not smart enough
There seems to be some problem with mime types config as defined in the config.php

This was partly resolved by changing: 'images' => "*.img", to 'images' => "",

It seemed that the actual $file was empty though.

Its not clear if the WYSIWYG URLS used in Civi are absolute either or if TinyMCE confog will always make them relative......