title: VS Code not recognizing Jest, underlining with Intellisense
body: <p>I'm using VS Code in a Typescript project that uses Jest for testing.  For some reason, VS Code thinks that the Jest globals are not available:</p>
  
  <p><a href="https://i.stack.imgur.com/68tun.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/68tun.jpg" alt="VS Code intellisense underlining Jest in red"></a></p>
  
  <p>I have the Jest typedefs installed in my dev dependencies.</p>
  
  <pre><code>"devDependencies": {
      // ...truncated
      "@types/jest": "^20",
      "jest": "^20.0.4",
      "ts-jest": "^20.0.7",
      "ts-node": "^5.0.0",
      "typescript": "~2.4.0"
  }
  </code></pre>