test: add "unsupported" property to examples

When truthy, the example is not rendered.

This allows for less conflicts when merging examples from upstream.

Author: aleclarson

RNTester/js/RNTesterExampleContainer.js

@@ -19,6 +19,9 @@ const RNTesterPage = require('./RNTesterPage');
 
 class RNTesterExampleContainer extends React.Component {
   renderExample(example, i) {
+    if (example.unsupported) {
+      return null;
+    }
     // Filter platform-specific examples
     var {title, description, platform} = example;
     if (platform) {