Automate cron setup for shooting warning emails

[hugocorbucci]

Using the rake task to shoot warning emails to people who's registration is about to be cancelled is not automated via puppet.
As a consequence, new machines won't have the cronjob necessary. That's bad.
So we need to automate the job that has been manually set up:

#!/usr/bin/env bash
source /etc/profile
export RAILS_ENV=production
cd /srv/apps/registrations/current
/usr/local/rvm/gems/ruby-2.3.0@global/bin/bundle exec rake registration:warn
/usr/local/rvm/gems/ruby-2.3.0@global/bin/bundle exec rake registration:cancel
/usr/local/rvm/gems/ruby-2.3.0@global/bin/bundle exec rake registration:process_queue

With cron schedule
*/5 * * * * script.sh > /dev/null