Fix Deleted node are still return by the API

Fix #529

gns3server/controller/project.py

@@ -140,6 +140,12 @@ class Project:
             return node
         return self._nodes[node_id]
 
+    @asyncio.coroutine
+    def delete_node(self, node_id):
+        node = self.get_node(node_id)
+        del self._nodes[node.id]
+        yield from node.delete()
+
     def get_node(self, node_id):
         """
         Return the node or raise a 404 if the node is unknown

gns3server/handlers/api/controller/node_handler.py

@@ -260,6 +260,5 @@ class NodeHandler:
         description="Delete a node instance")
     def delete(request, response):
         project = Controller.instance().get_project(request.match_info["project_id"])
-        node = project.get_node(request.match_info["node_id"])
-        yield from node.destroy()
+        yield from project.delete_node(request.match_info["node_id"])
         response.set_status(204)