Minor Description
Add support for LDAP based authentication rather than password based.
Initial efforts to simply support search for the dn based on the passed username, followed by "simple" authentication of that dn using the password supplied.
Given the fact that the password must be sent in the clear over the client <-> qpid broker connection for this to work, this authentication method should ONLY be used on SSL secured connections.
For LDAP servers that support SASL authentication we might in future be able to proxy the SASL exchange through the AMQP sasl mechanism.
