use the new style of string formatting

- Using the % to format the strings is in the process of being
  deprecated. It's recommended that the new style (defined by
  PEP #3101[1]) be used for new code moving forward.

[1] http://docs.python.org/3.0/whatsnew/2.6.html#pep-3101

totp.py

@@ -45,7 +45,7 @@ def __init__ (self, confFile):
       Code = unpack('>L', ShortHash)[0]
       Code &= 0x7FFFFFFF
       Code %= 1000000
-      Code = "%06d" % Code
+      Code = '{0:06d}'.format(Code)
       self.keys.append(Code)
 
   def authenticate(self, Code):