Adds outline of go-micro Tunnel interface

tunnel/tunnel.go

@@ -0,0 +1,15 @@
+// Package tunnel provides micro network tunnelling
+package tunnel
+
+import (
+	"github.com/micro/go-micro/transport"
+)
+
+// Tunnel creates a p2p network tunnel.
+type Tunnel interface {
+	transport.Transport
+	// Connect connects the tunnel
+	Connect() error
+	// Close closes the tunnel
+	Close() error
+}