[hack/vm] add self.vm dict

uncloud/hack/vm.py

@@ -77,6 +77,8 @@ class VM(object):
         self.ifdown = os.path.join(self.hackprefix, "ifdown.sh")
         self.ifname = "uc{}".format(self.mac.to_str_format())
 
+        self.vm = {}
+
     def get_qemu_args(self):
         command = (
             "-name {owner}-{name}"