decode signature to a str

bigchaindb/core.py

@@ -627,7 +627,7 @@ class Bigchain(object):
 
         vote_signed = {
             'node_pubkey': self.me,
-            'signature': signature,
+            'signature': signature.decode(),
             'vote': vote
         }
 

tests/pipelines/test_vote.py

@@ -33,6 +33,7 @@ def test_vote_creation_valid(b):
     assert vote['vote']['is_block_valid'] is True
     assert vote['vote']['invalid_reason'] is None
     assert vote['node_pubkey'] == b.me
+    assert isinstance(vote['signature'], str)
     assert crypto.PublicKey(b.me).verify(serialize(vote['vote']).encode(),
                                             vote['signature']) is True