Add package name / bundle ID to bundle URL in development

Summary:
Adds the package name (Android) / bundle ID (iOS) as a new URL parameter named `app` in the bundle URL. This currently has no effect on Metro, which will ignore it for bundling / caching purposes.

Changelog: [General] - Add package name / bundle ID to bundle URL in development

Reviewed By: cpojer

Differential Revision: D21429764

fbshipit-source-id: 394fe50dba72219f7594ebeac9486a8264a836a6

ReactAndroid/src/main/java/com/facebook/react/devsupport/DevServerHelper.java

@@ -421,12 +421,13 @@ public class DevServerHelper {
   private String createBundleURL(String mainModuleID, BundleType type, String host) {
     return String.format(
         Locale.US,
-        "http://%s/%s.%s?platform=android&dev=%s&minify=%s",
+        "http://%s/%s.%s?platform=android&dev=%s&minify=%s&app=%s",
         host,
         mainModuleID,
         type.typeID(),
         getDevMode(),
-        getJSMinifyMode());
+        getJSMinifyMode(),
+        mPackageName);
   }
 
   private String createBundleURL(String mainModuleID, BundleType type) {