Add Jack in Showcase

Summary:
Hi, I fixed the indentation.

Regarding the infoLink tag, isn't my article on medium following your guidelines ? We are a startup, and I'm talking about our switch to your technology (https://medium.com/herdani/our-switch-to-react-native-f4ada19f0f3d#.ogwjzf2tw)

Thanks and regards
Closes https://github.com/facebook/react-native/pull/11787

Differential Revision: D4456666

Pulled By: hramos

fbshipit-source-id: ac25757b4ef75533c64bbe941c0059aa76835c6b

website/src/react-native/showcase.js

@@ -346,6 +346,14 @@ var featured = [
     infoLink: 'https://medium.com/@jesusdario/developing-beyond-the-screen-9af812b96724#.ozx0xy4lv',
     infoTitle: 'How React Native is helping us to reinvent the wheel',
   },
+  {
+    name: 'Jack',
+    icon: 'https://s3-eu-west-1.amazonaws.com/jack-public/react-native-showcase/jack-raw-icon.png',
+    linkAppStore: 'https://itunes.apple.com/us/app/you-have-a-jack/id1019167559?ls=1&mt=8',
+    linkPlayStore: 'https://play.google.com/store/apps/details?id=com.jack45.jack',
+    infoLink: 'https://medium.com/@herdani/our-switch-to-react-native-f4ada19f0f3d#.ogwjzf2tw',
+    infoTitle: 'Our switch to React Native',
+  },
 ];
 
 /*