Update mail_room.

Gemfile.lock

 GIT
   remote: git://github.com/DouweM/mail_room.git
-  revision: b9deb6430ca13b2d44676827c45476d76966922c
+  revision: c17c74cdef55dcd962333545fdb4d6e496cd9050
   branch: sidekiq
   specs:
     mail_room (0.3.1)

Procfile

 web: bundle exec unicorn_rails -p ${PORT:="3000"} -E ${RAILS_ENV:="development"} -c ${UNICORN_CONFIG:="config/unicorn.rb"}
 worker: bundle exec sidekiq -q post_receive -q mailer -q archive_repo -q system_hook -q project_web_hook -q gitlab_shell -q incoming_email -q common -q default
-mail_room: bundle exec mail_room -c config/mail_room.yml
+mail_room: bundle exec mail_room -q -c config/mail_room.yml