Add back itertools
Add back itertools

This was removed when I rebase removed my py3k support changes
as @brutasse opened #70 long before I had this all ready to merge.

obfuscurity/whisper,akbooer/whisper,piotr1212/whisper,deniszh/whisper,penpen/whisper,alexandreboisvert/whisper,graphite-project/whisper,jjneely/whisper,cbowman0/whisper,graphite-server/whisper,kerlandsson/whisper