title: RN 0.21.0 "Debug JS" doesn't work
body: <p>I upgrade RN to 0.21.0 with command <code>npm install --save react-native@0.21</code>.</p>
  
  <p>Then, "Debug JS" doesn't work , and throws exception "Unable to connect with remote debugger", But RN 0.20.0 is OK.</p>
  
  <p><code>npm: 2.14.15</code></p>
  
  <p><code>node: v5.3.0</code></p>
  
  <p><code>watchman: 4.4.0</code></p>
  
  <p><code>flow: 0.22.1</code></p>
  
  <p><code>React Developer Tools: 0.14.8</code></p>
  
  <p><a href="http://i.stack.imgur.com/MWYGi.png" rel="nofollow">error image</a></p>