postfix:
* Move common packages installation in common.yml
* Replace ansible_fqdn by evolinux_fqdn, set postfix_slow_transport_include to false by default (only for packmails and packwebs)
* Remove dependency on evolinux_fqdn var
* Do not overwrite main.cf if it has been modified (except if postfix_force_main_cf)
evolinux-base:
* Move exim4 purge from evolinux-base to postfix role
* Call postfix role call after nagios role (dependency)