Fix typo

comma , instead of percent % made %s render in front of the message.

Author: weex

examples/sign-message.py

@@ -24,7 +24,7 @@
 
 print(key, address)
 print("Address: %s" % address)
-print("Message: %s", message)
+print("Message: %s" % message)
 print("\nSignature: %s" % signature)
 print("\nVerified: %s" % VerifyMessage(address, message, signature))