Do not send "addr" twice to clients sending "verack"
Do not send "addr" twice to clients sending "verack"

In order to handle peers that omit the "verack" message
 #complete_handshake is called both on "version" and "verack" messages.

Until now this method triggered an "addr" command to the peer
unconditionally, though, so proper clients received the message twice.

Zlerp/bitcoin-ruby,georgemillo/bitcoin-ruby,bitpesa/bitcoin-ruby,xiumiao/bitcoin-ruby,robertg/bitcoin-ruby,mhanne/bitcoin-ruby,tarix/bitcoin-ruby,assafshomer/bitcoin-ruby