[bug 965475] Add l10n_completion script

This figures out the percent translated of strings broken down by
locales and by app.
Add cron-related stuff to deploy
Fix .po data merging in l10n_completion.py

This applies the changes I just made to the kitsune version so that it's
correctly merging numbers between .po files in a given locale.

It also provides locale-level percent completed numbers.