Identifiing files / names to elements

Add a plugin type that allows to XDM to identify a file as an element in XDM
these plugins would be restricted to one MediaTypeManager

they would need a location config field and make only sense with an "element config"

these plugins could set a status for the found Element and report the location to XDM, they could also be used to identify names from RSS feeds or other locations!

NOTE: for XDM to be location aware changes have to be made (another idea)