Restart the application on every reboot

This way we don't have to start it manually every time the server is
restarted.

Note if we start the application with `bin/rails s start -e production`,
as we'd probably want to do so this task doesn't depend on the server we
use, the application will crash when we restart it because it will be
restarted in the development environment. Maybe this issue will be fixed
in future versions of Rails and/or Puma.

Also note we're passing `2` workers to delayed job, and this number must
be the same number we use for the `delayed_job_workers` variable in
capistrano. I haven't found a way to share this variable between
whenever and capistrano.

config/schedule.rb

@@ -39,3 +39,9 @@ end
 every 1.day, at: "3:00 am", roles: [:cron] do
   rake "votes:reset_hot_score"
 end
+
+every :reboot do
+  command "cd #{@path} && bundle exec puma -C config/puma/#{@environment}.rb"
+  # Number of workers must be kept in sync with capistrano's delayed_job_workers
+  command "cd #{@path} && RAILS_ENV=#{@environment} bin/delayed_job -n 2 restart"
+end