server: request addresses from new peers once they can process messages
server: request addresses from new peers once they can process messages

This was previously done within the OnVersion listener, which should not
be a blocking operation. It turns out that requesting these messages
there can lead to blocking due to peers not being able to process
messages since their message queues have yet to start. Therefore, we'll
now request within handleAddPeerMsg, which should allow it to go
through.

davecgh/btcd,dajohi/btcd,tb00/btcd,dajohi/btcd,btcsuite/btcd,btcsuite/btcd,dajohi/btcd,ltcsuite/ltcd,tb00/btcd,davecgh/btcd,ltcsuite/ltcd