Add method for voter interface

DecisionSystem/voter.py

@@ -1,7 +1,13 @@
 from Messaging.packmessage import PackMessage
+import umsgpack
 
 class Voter:
+    def __init__(self):
+        # self._client = 
+        pass
+
     def submit_vote(self, vote_contents):
-        NotImplementedError
-
+        raise NotImplementedError()
 
+    def request_vote(self):
+        raise NotImplementedError()