Include DelayedJob errors in Errbit exceptions

The integration between Airbrake/Errbit and DelayedJob wasn't working
because we require our dependencies in alphabetic order, and so by the
time `airbrake` was required, `delayed_job` wasn't loaded.

So we're manually requiring the integration.

config/initializers/errbit.rb

@@ -1,3 +1,5 @@
+require "airbrake/delayed_job" if defined?(Delayed)
+
 Airbrake.configure do |config|
   config.host = Rails.application.secrets.errbit_host
   config.project_id = Rails.application.secrets.errbit_project_id