Add support for appliance format version 8

gns3server/controller/appliance.py

@@ -44,6 +44,10 @@ class Appliance:
     def status(self):
         return self._data["status"]
 
+    @property
+    def registry_version(self):
+        return self._data["registry_version"]
+
     @property
     def symbol(self):
         return self._data.get("symbol")