Added dnspython error type to error messages in the lookup module

Ignore-this: cc71fec031c63be27d9210ac58bc276

darcs-hash:20090407113135-1e3d8-af9b58858a613ab056b1e1c1d7224ca7e20b8968
Don't register in sip_message.py when sending

darcs-hash:20090407113047-58103-01573c7afcac11b79498ee361b5cff66633aa3fc