fix bug with hex_to_int; remove unused function

lib/util.py

@@ -5,10 +5,6 @@ from datetime import datetime
 is_verbose = True
 
 
-def hex_to_int(s):
-    return int('0x' + s[::-1].encode('hex'), 16)
-
-
 class MyEncoder(json.JSONEncoder):
     def default(self, obj):
         from transaction import Transaction