title: Webpack dev server - having to change port every time I run it
body: <p>I'm new to webpack-dev-server, and Im using it as part of test project in React.</p>
  
  <p>When I start the server first time, it works as expected. (I use an npm script to run it up via webpack.config.js)</p>
  
  <p>In the Mac terminal window, when I want to close the server I use CTRL-Z and the server seems to terminate.</p>
  
  <p>If I then run the server again I get</p>
  
  <p>Error: listen EADDRINUSE 127.0.0.1:5001
  ........</p>
  
  <p>So the server didnt terminate it seems. So in order to run it up again, I have to choose a different port in webpack.config.js.</p>
  
  <p>Then if I kill it and start again, I need to change ports again (and again, and again etc) - its bonkers.</p>
  
  <p>Clearly I must be doing something stupid - can anyone help me out ?</p>
  
  <p>Thanks</p>