update scripts for python3

scripts/get_history

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import sys
 from electrum import Network
@@ -7,7 +7,7 @@ from electrum.util import json_encode, print_msg
 try:
     addr = sys.argv[1]
 except Exception:
-    print "usage: get_history <bitcoin_address>"
+    print("usage: get_history <bitcoin_address>")
     sys.exit(1)
 
 n = Network()