Fix i18n deprecation warning
Switch to errbit
Merge pull request #149 from alphagov/errbit

Switch to errbit
Update whenever

The crontab was failing to generate on Ruby 2.0 due to an outdated
version of Chronic
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.