Prevented a connection from being done twice

On node 0.10.8 the example script would throw:

    dgram.js:163
        throw new Error('Socket is already bound');
          ^
    Error: Socket is already bound
        at Socket.bind (dgram.js:163:11)
        at Client.connect (/test.js:94:15)
        at /node_modules/nat-pmp/index.js:57:12
        at process._tickCallback (node.js:415:13)
        at Function.Module.runMain (module.js:499:11)
        at startup (node.js:119:16)
        at node.js:901:3