Media manager Directory doesn't update while browsing folders

Reason: popup manager alters folderlist element value directly, doesn't trigger 'change' event. Need to update chosen.jquery state manually.

Solution:
jQuery( folderlist ).trigger('liszt:updated');

Note:
Cannot use `jQuery(this.folderlist).trigger('change');`, as this would cause a loop (element is listening to change event -> Maximum call stack size exceeded)

Issue tracker: http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=29252