Add MySQL port, fixes #4

[lumbric]

I don't undestand why this ever worked before, but this fix seems to work for me. Also it is a nice thing to be able to select port via argument on CLI.

[skwashd]

While this fixes #4 it also contains a commit from #6. I have proposed #10 that fixes the port issue. To keep it consistent with the other values being concatenated into the string I used a pointer.