Ticket 436 - nsds5ReplicaEnabled can be set with any invalid values.
Bug Description: There is no checking of the value for nsds5ReplicaEnabled either
at startup or with ldapmodify.
Fix Description: Verify the value is either "on" or "off", and report the
appropriate error message.
https://fedorahosted.org/389/ticket/436
Reviewed by: richm(Thanks!)