We explicitely set the MySQL connection port, even if it is the default
one. I don't think this solves anything, but it's a good idea to
set the port explicitely, generally speaking.
Xqueue containers consist of two services: a gunicorn service, that
receives requests from LMS/CMS, and a worker service. I guess the worker
service receives orders from the gunicorn service, through rabbitmq.
(but I'm less than certain about that).
While adding xqueue containers, we refactored the way mysql databases
are created, and how the root password is loaded. Also, we silenced some
options from the configure script.
