Fix for proxy exiting early

When a proxied core service was accessed before it was ready
to accept a connection, due to a start-up, restart, etc of
a core service, then the proxy exited instead of continuing
to accept new connections.

This meant having to restart faasd and hope the race condition
worked itself out, or that no incoming requests were made.

Tested with Grafana, which seemed to manifest the issue
the most.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

pkg/proxy.go

@@ -86,7 +86,7 @@ func (p *Proxy) Start() error {
 			conn.Close()
 
 			log.Printf("Unable to dial: %s, error: %s", upstreamAddr, err.Error())
-			return err
+			continue
 		}
 
 		go pipe(conn, upstream)