Fix demo for Android

sample/HelloFacebook/android/app/src/main/java/com/hellofacebook/MainApplication.java

@@ -56,7 +56,7 @@ public void onCreate() {
 
   private final ReactNativeHost mReactNativeHost = new ReactNativeHost(this) {
     @Override
-    protected boolean getUseDeveloperSupport() {
+    public boolean getUseDeveloperSupport() {
       return BuildConfig.DEBUG;
     }