LDAP: Add the wildcard_limit option
    
    Related:
        https://fedorahosted.org/sssd/ticket/2553
    
    Adds a new wildcard_limit option that is set by default to 1000 (one
    page). This option limits the number of entries that can by default be
    returned by a wildcard search.
    
    Reviewed-by: Pavel Březina <pbrezina@redhat.com>