Import/Export Libraries

Import and Export content libraries via XML.
It might make sense to factor out kind of helper method that would actually do the work so this method's only responsibility is to call helper with correct parameters, something like.

Helper might look something like 

    def import_courselike(request, subdir, fname, loader):
        ....
And be called something like

     course_items = import_courselike(request, subdir, "library.xml", import_library_from_xml)

BUt this might have no benefit over what we have now, so it's up to you :)