[btcsuite/btcd] a1f014: peer: Track and return advertised protocol version

[Dave Collins]

  Branch: refs/heads/master
  Home:   https://github.com/btcsuite/btcd
  Commit: a1f014c9e180a5ae53e3a60d53b1b2ecfeccf664
      
https://github.com/btcsuite/btcd/commit/a1f014c9e180a5ae53e3a60d53b1b2ecfeccf664
  Author: Dave Collins <da...@conformal.com>
  Date:   2016-10-28 (Fri, 28 Oct 2016)

  Changed paths:
    M peer/peer.go

  Log Message:
  -----------
  peer: Track and return advertised protocol version

This adds a new field to the peer struct which stores the protocol
version advertised by the remote peer and updates the StatsSnapshot to
return the advertised version instead of the negotiated version.