buster-server says "running" even if address is already in use

[dkl-ppi]

Starting buster-server twice produces the following output for me on my windows machine:

Address already in use. Pick another port with -p/--port to start buster-server
buster-server running on http://localhost:1111

The second message isn't displayed on my linux machine. I don't know whether it is the OS or node.js version which makes the different.

I have seen that we use process.nextTick() in buster-server-cli\lib\server-cli.js. I think using a callback for server.listen instead, would be better and solve this problem.

[GCheung55]

Please take a look at the PR.

[dkl-ppi]

Fixed in version 0.3.2 of buster-server-cli.