Change how active_mailer is configured.

Also requires changes to config/mailer.yml (Not checked in) which looks
like this:

default: &default
  user_name: XXXX
  password: XXXX
  address: XXXX
  port: 25
  authentication: :login
  enable_starttls_auto: true
development:
  <<: *default
production:
  <<: *default
Use AWS::SES For Action mailer
Configure exception notifier to send mail to authoring-help@concord.org
Configure routes for testing mail sending and exception reporting.