ensure the email job is managed effectively

currently the email job is running in tmux in the ubuntu box (that is dokku av), but suffers in that it will die when the ubuntu box is rebooted

Could we have an entrypoint from docker just hit `bundle exec rake jobs:work` (or just a Procfile?)

### related info

https://binarapps.com/blog/pair-programming-with-docker-ssh-and-tmux/

### attach to existing tmux

$ ssh av-ssh
$ tmux attach
$ Ctrl-b d

### create a tmux

$ ssh av-ssh
$ tmux attach
$ bundle exec rake jobs:work