Fixed Android Lint warning in AndroidManifest.xml.
diff --git a/android-project/AndroidManifest.xml b/android-project/AndroidManifest.xml
index ce7c056..d9460bf 100644
--- a/android-project/AndroidManifest.xml
+++ b/android-project/AndroidManifest.xml
@@ -19,7 +19,8 @@
     -->
     <application android:label="@string/app_name"
                  android:icon="@drawable/ic_launcher"
-	         android:theme="@android:style/Theme.NoTitleBar.Fullscreen">
+                 android:allowBackup="true"
+                 android:theme="@android:style/Theme.NoTitleBar.Fullscreen">
         <activity android:name="SDLActivity"
                   android:label="@string/app_name">
             <intent-filter>