Can set the default mode for folder creation.

Tracker: http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=32566&start=25

This adds a way for the default folder creation mode to be changed at run time. This way, if someone needs to use a different mode, they can write a small plugin which will set the default mode to whatever they prefer and this mode will be used when folders are created (in the media manager, for example).