add socket-pair as dep

package.json

@@ -65,6 +65,7 @@
     "serve-index": "^1.7.0",
     "serve-static": "^1.10.0",
     "server-destroy": "^1.0.1",
+    "socket-pair": "^1.0.0",
     "stream-pair": "^1.0.3",
     "stunnel": "git+https://git.daplie.com/Daplie/node-tunnel-client.git#v1"
   }