Make sure Producer can recover from IO error on ReadUnpackedResponse

[judwhite]

Logs are inconclusive in this case. Induced by leaving in break-all for a few minutes.

[2016-10-15 05:57:19.5504] [Error] P1 (127.0.0.1:4150) IO error on ReadUnpackedResponse - System.ArgumentException: length of response is too small
Parameter name: response
   at NsqSharp.Core.Protocol.UnpackResponse(Byte[] response, FrameType& frameType, Byte[]& body) in D:\Projects\_github\NsqSharp\NsqSharp\Core\Protocol.cs:line 104
   at NsqSharp.Core.Protocol.ReadUnpackedResponse(IReader r, FrameType& frameType, Byte[]& body) in D:\Projects\_github\NsqSharp\NsqSharp\Core\Protocol.cs:line 122
   at NsqSharp.Core.Conn.readLoop() in D:\Projects\_github\NsqSharp\NsqSharp\Core\Conn.cs:line 555
[2016-10-15 05:57:19.6231] [Info] P1 (127.0.0.1:4150) beginning close
[2016-10-15 05:57:19.6927] [Info] P1 (127.0.0.1:4150) breaking out of writeLoop
[2016-10-15 05:57:19.6927] [Info] P1 (127.0.0.1:4150) writeLoop exiting
[2016-10-15 05:57:19.7113] [Info] P1 (127.0.0.1:4150) readLoop exiting
[2016-10-15 05:57:19.8471] [Info] P1 (127.0.0.1:4150) clean close complete
[2016-10-15 05:57:19.8471] [Info] P1 (127.0.0.1:4150) finished draining, cleanup exiting
[2016-10-15 05:57:20.0172] [Info] P1 exiting router