Set up mailer using ActiveJob and Resque

* Change rails to use edge rails (need for ActiveJob)
* Add resque and resque-scheduler gem
  * Setup resque config
  * Setup resque and resque-scheduler rake task
* Setup ActiveJob config to use resque
  * Create Jobs
    * Welcome email
      * Run after Baker created
* Add mailcatcher gem
  *  Add config to development environment
     so that emails are intercepted

NB: Need redis server running for this to work

* http://redis.io/download

USAGE:

* mailcatcher
* QUEUE=* rake environment resque:work
* rake environment resque:scheduler
* rails s

Resque dasbhoard:

* resque-web
* http://127.0.0.1:5678

Mailcatcher dashboard:

* http://127.0.0.1:1080