Feature multi process as deb service [upstart version]

As discussed in #145 here is my proposition about #144 based on upstart.
I loose some of my hair on it but it works.

I use a main service managing "worker" services with ports number as upstart instances

$force_start became $force because it is used also to stop service (#MSWindowsStartMenuEffect)

And the enable=0 should be (or not ... #Shakespeare) anything but 0 to allow start.

One thing annoying me is that ```restart thumbor``` fails because upstart does not read conf file for restart (just kill and respawn the process witch does nothing as a virtual service)