Add vote property to submit vote and change null values of init parameters

DecisionSystem/messages.py

@@ -1,7 +1,7 @@
 import umsgpack
 
 class Message:
-    def __init__(self, sender = None, data = None):
+    def __init__(self, sender = "", data = {}}):
         self._sender = sender
         self._data = data
 
@@ -60,3 +60,13 @@ class CommanderWill(Message):
 
 class SubmitVote(Message):
     _type = "vote"
+
+    @property
+    def vote(self):
+        return self._data["vote"]
+
+    @vote.setter
+    def vote(self, value):
+        self._data["vote"] = value
+
+