Fix python style issues reported by flake8

Additionally some python2-only "print" statements are now compatible
with python3.

plugins/currency/bitcoin/bitcoind_

@@ -236,7 +236,7 @@ class Proxy:
             'method': self.method,
             'params': args,
             'id': self.id,
-            }
+        }
         request = urllib.request.Request(self.service.url, json.dumps(data).encode())
         if self.service.username:
             auth_string = '%s:%s' % (self.service.username, self.service.password)