update_link had wrong arg order

Author: stuartmarsden

daemon/core/emulator/coreemu.py

@@ -378,7 +378,7 @@ def delete_link(self, node_one_id, node_two_id, interface_one_id, interface_two_
             if node_two:
                 node_two.lock.release()
 
-    def update_link(self, node_one_id, node_two_id, link_options, interface_one_id=None, interface_two_id=None):
+    def update_link(self, node_one_id, node_two_id, interface_one_id=None, interface_two_id=None, link_options=LinkOptions()):
         """
         Update link information between nodes.