media management xml - only allow setting name for media elements that already exist.  This prevents media entries from being created (e.g. if loading XML) if no actual file exists on disk.
media management xml - synchronize updates to media elements, so element won't be added/removed during external name change event handling
media management xml - add directory monitor for top managed directory, for media type directory creation/deletion; update monitor and update code handling lower level media dirs.
This update should allow any media directory (html/images, html/videos/ html/customhtml) to have first-level directories added or removed (e.g. create new directory html/images/sponsor_banner and add images to it) and the sb dynamically updates with the new media type and media files