Revert "switch from `curb` to `faraday`" - was causing problems with ssl

This reverts commit 691d92eb4056a3f6e7dd34aa3180b083f037f0e3.
Add applied_at and filesize to update response
Merge pull request #170 from bitzesty/revert_faraday

Revert faraday & add new fields for tariff updates
README update