disable all daemons managed by zentyal to have manual control over them

to avoid the start; stop; start sequence that makes the boot process slow
Merge branch 'master' into jacalvo/override-daemons

Conflicts:
	main/core/ChangeLog
	main/dhcp/ChangeLog
	main/ntp/ChangeLog
	main/squid/ChangeLog
	main/webserver/ChangeLog
silent disable/stop of overriden daemons
Merge pull request #330 from Zentyal/jacalvo/override-daemons

disable all daemons managed by zentyal to have manual control over them