Keep all roles in calendar folder ACLs

Instead of keeping only the highest access roles. This reverts
2c678101 to fix handling of ACLs with multiple groups.

This is done because OpenChange library stores other roles/permissions
in the ACLs that have limited scope to the MAPI protocol and it
maintains an homogeneous returned data with other folders by returning
the actual data is stored in the DB.

By sorting the roles, we give the ability to callers to validate
permissions more efficiency (less loops) and keep the right highest
access level. As an example, check
[SOGoApppointmentFolder:roleForComponentsWithAccessClass:forUser]
for details.