Fix OPTIONS responses: Remove all HEAD methods as they return errors. Do not advertise writable method for class/id/properties path if property is read only (i.e. protected prop). Collections do not have PUT, PATCH, DELETE (delete is accepted but always returns 400 code).

try:
    # Python 3+.
    from xmlrpc import client, server
    server.SimpleXMLRPCDispatcher
except (ImportError, AttributeError):
    # Python 2.
    import xmlrpclib as client
    import SimpleXMLRPCServer as server