res: Replace the custom ExtendedViewPager widget with stock ViewPager.

src/main/res/layout/preview_image_activity.xml

@@ -23,7 +23,7 @@
     android:layout_height="match_parent"
     android:clickable="true" >
 
-    <com.ortiz.touch.ExtendedViewPager
+    <android.support.v4.view.ViewPager
         android:id="@+id/fragmentPager"
 		android:layout_width="match_parent"
 		android:layout_height="match_parent"