send RPL_LOGGEDIN to target_p upon ENCAP SU

[jesopo]

intended usecase: a client receives RPL_LOGGEDIN post-registration on a network that supports SASL but the client knows it doesn't currently have a SASL configuration, so it prompts the user with "would you like to save your account password for this network?"

[edk0]

This sends a RPL_LOGGEDIN for (null) if I log out. It should probably send RPL_LOGGEDOUT or nothing