title: Exclude with pattern in tsconfig.json
body: <p>Is there any way to add a pattern in the exclude property of a tsconfig file or is it only able to support directories?</p>
  
  <p>I'm trying to exclude all my test files from compilation so I was wondering if I can use something like this :</p>
  
  <pre><code>src/**/*.spec.ts
  </code></pre>
  
  <p>Seems like it doesn't work though.</p>