title: Upgrade Expo CLI have unknown error --assetPlugins
body: <p>I upgrade to latest Expo CLI 2.19.2 and tried upgrade my expo application using SDK 33. </p>
  
  <p>When I called expo start, i have a message saying: </p>
  
  <blockquote>
    <p>Opening DevTools in the browser... (press shift-d to disable) error: unknown option `--assetPlugins'</p>
    
    <p>Metro Bundler process exited with code 1 Set EXPO_DEBUG=true in your
    env to view the stack trace.</p>
  </blockquote>
  
  <p>I tried to set EXPO_DEBUG=true on Mac but doesn't show any debugging details when running expo start again.</p>
  
  <p>I found it i should called export EXPO_DEBUG=true </p>
  
  <p>Here is additional message:</p>
  
  <blockquote>
    <p>error: unknown option `--assetPlugins'</p>
    
    <p>Metro Bundler process exited with code 1 Error: Metro Bundler process
    exited with code 1
        at ChildProcess. (/@expo/xdl@54.1.2/src/Project.js:1598:16)
        at Generator.next ()
        at step (/Users/simonlam/.nvm/versions/node/v11.6.0/lib/node_modules/expo-cli/node_modules/@expo/xdl/build/Project.js:2347:191)
        at /Users/simonlam/.nvm/versions/node/v11.6.0/lib/node_modules/expo-cli/node_modules/@expo/xdl/build/Project.js:2347:437
        at new Promise ()
        at ChildProcess. (/Users/simonlam/.nvm/versions/node/v11.6.0/lib/node_modules/expo-cli/node_modules/@expo/xdl/build/Project.js:2347:99)
        at ChildProcess.packagerProcess.once (/@expo/xdl@54.1.2/src/Project.js:1595:5)
        at Object.onceWrapper (events.js:276:13)
        at ChildProcess.emit (events.js:188:13)
        at Process.ChildProcess._handle.onexit (internal/child_process.js:254:12)</p>
  </blockquote>