Fixed setSecurityGroup so it does nothing if the group is already a distribution group and setSecurityGroup is false
Merge branch '3.2' into cperello/distribution-groups-modification-fixes

Conflicts:
	main/users/ChangeLog
simplified the logic opearation with an xor
Merge pull request #786 from Zentyal/cperello/distribution-groups-modification-fixes

Cperello/distribution groups modification fixes