Remove the usage of "sudo" in the fpm and apache-php images

[damien-carcel]

Q	A
Bug report?	no
Feature request?	yes
BC Break report?	no
RFC?	no
Affected image and tag	akeneo/fpm and akeneo/apache-php, all tags

Currently, the processes of these two images are run with sudo (through the CMD instruction). This is a remnant from when the images had docker as the default user (as was the comment that was removed in #319).

This is probably now useless as the default user is root. However, a default user can be specified through the user option (both docker run and compose file). We need to be sure removing the use of sudo in CMD will not prevent the container from running in such a case.

This issue is link to #227 too.

[damien-carcel]

Closing.

As long as the docker user exists (and it will not disapear), sudo is needed to be sure FPM is launched properly.