re-add missing methods

src/com/owncloud/android/ui/activity/WhatsNewActivity.java

@@ -167,12 +167,22 @@ public class WhatsNewActivity extends FragmentActivity implements ViewPager.OnPa
                 );
     }
 
+    @Override
+    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
+        // unused but to be implemented due to abstract parent
+    }
+
     @Override
     public void onPageSelected(int position) {
         mProgress.animateToStep(position+1);
         updateNextButtonIfNeeded();
     }
 
+    @Override
+    public void onPageScrollStateChanged(int state) {
+        // unused but to be implemented due to abstract parent
+    }
+
     private final class FeaturesViewAdapter extends FragmentPagerAdapter {
 
         private FeatureItem[] mFeatures;