Allow disablement of net_plugin's listen socket
Allow disablement of net_plugin's listen socket

Disable net_plugin's listen socket when p2p-listen-endpoint is empty. This is useful for security and for an easier way of running multiple nodeos without it conflicting when you don't actually need to service incoming connections.

EOSIO/eos,EOSIO/eos,EOSIO/eos,EOSIO/eos,EOSIO/eos