Revert "Only run tariff sync once a day at 01:23"

This reverts commit b21cac649e2907a53784fb0f15fdf8ae08441552.
switch from `curb` to `faraday`

Moving to `faraday` because curb sometimes raises *Host Resolution Error*

[pivotal story](https://www.pivotaltracker.com/n/projects/488191/stories/69001522)
Merge pull request #162 from bitzesty/69001522-faraday

switch from `curb` to `faraday`
Retry downloading update if update file is missing

When Tariff runs in multiserver environment one server may have
downloaded the update and marked as pending. If other server tries to
apply it, it won't find the file. Therefore we try to redownload if file
is missing.
fix specs
Merge pull request #161 from bitzesty/65969536-download-missing-updates

Retry downloading update if update file is missing
Add guidance for contributors
Switch to redis-semaphore

According to issue #68435604 (PT) we experience some problems
that might be connected with our locking mechanism.

It seems that redis-semaphore is more stable and popular solution
among Sidekiq + Redis locking mechanisms. Thus, I decided to
give it a try.
Merge pull request #164 from bitzesty/semaphore

Switch to redis-semaphore
add ROIMB4 conformance rule

on `BaseRegulation`
>The referenced regulation group must exist
Merge pull request #165 from bitzesty/ROIMB4

add ROIMB4 conformance rule
Add Contributing and Licence sections to README

Also update the ruby version to 2.0.0 and include the other repos used by the tariff.
Remove double locking