Remove unused handlers for messages negotiate_pubkey and response_pubkey
Remove unused respond_pubkey_if_mine from transport.py
Remove unused Cryptor field in CryptoTransportLayer
Merge pull request #1016 from yagoulas/unused_messages

Remove unused message handlers
Remove dead code from orders.

* Remove unused import.
Remove dead code from openbazaar_daemon.
Remove dead code from network_util.
Remove dead code from ws.
Remove dead code and unused attributes from dht.
Remove dead code and unused attributes from connection.
Remove dead code from multisig.
Remove dead code from market.
Remove unused attribute from ec test.