org/cron.py: Add monthly commit stats fetching
Adds monthly commit stats fetching into fetch_org using parameter monthly_run using IGitt's lazy_get.
Upgrades IGitt to 0.4.1.dev20180105123616. Upgrades container coala/base to 0.11.
Sadly, GitHub API doesn't provide monthly data, instead it gives weekly data so I fetch data for the last 34 days.
Closes #44 .
Edited by Nalin Bhardwaj