Remove 'displayName' prop from 'PickerExample' component

Summary:The value of the displayName was wrong (had space in it). Also the babel plugin for display name already adds display names. So we shouldn't need to do it manually.

As a side effect, it breaks the UIExplorer app when HMR is enabled (that's how I found it).
Closes https://github.com/facebook/react-native/pull/6193

Differential Revision: D2987160

fb-gh-sync-id: fd64112c26741fab1385454a0ce978ec1eaf2415
shipit-source-id: fd64112c26741fab1385454a0ce978ec1eaf2415

Examples/UIExplorer/PickerAndroidExample.js

@@ -44,8 +44,6 @@ const PickerExample = React.createClass({
     };
   },
 
-  displayName: 'Android Picker',
-
   render: function() {
     return (
       <UIExplorerPage title="<Picker>">