[DATA RACE] Proxy fails when intermediary node restarts

[ivcosla]

When running proxy integration environment, if the intermediary node is restarted an a new request is issued to the proxy client, it hangs and this data race appears:

[2019-06-26T18:37:22+02:00] INFO [router]: Forwarded packet to App on Port 10
[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]: 2019/06/26 18:37:22 Copy error: connection write timeout
[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]: ==================
[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]: WARNING: DATA RACE[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]: Write at 0x00c0000f4010 by main goroutine:
[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]:   github.com/skycoin/skywire/internal/therealproxy.(*Client).ListenAndServe()
[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]:       /home/ivan/skycoin/skywire/internal/therealproxy/client.go:46 +0x39c
[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]:   main.main()[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]:       /home/ivan/skycoin/skywire/cmd/apps/therealproxy-client/therealpro
xy-client.go:62 +0x971
[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]:
[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]: Previous read at 0x00c0000f4010 by goroutine 49:[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]:   github.com/skycoin/skywire/internal/therealproxy.(*Client).ListenAndSe
rve.func1()[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]:       /home/ivan/skycoin/skywire/internal/therealproxy/client.go:65 +0x1
56[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]:
[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]: Goroutine 49 (running) created at:[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]:   github.com/skycoin/skywire/internal/therealproxy.(*Client).ListenAndSe
rve()
[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]:       /home/ivan/skycoin/skywire/internal/therealproxy/client.go:51 +0x2
e8
[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]:   main.main()
[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]:       /home/ivan/skycoin/skywire/cmd/apps/therealproxy-client/therealpro
xy-client.go:62 +0x971
[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]: ==================
[2019-06-26T18:37:22+02:00] INFO [socksproxy-client.v1.0]: 2019/06/26 18:37:22 yamux: connection write timeout