More PagedView cleanup

-> Custom content screen is now full screen (with some padding inserted for now)
-> Hiding the hotseat and page indicators when scrolling to the
   custom content screen
-> Adding background scrim fade in to custom content space.

Change-Id: I28921318a38af46f11fa836020a590c70d5d96ed

src/com/android/launcher3/SmoothPagedView.java

@@ -130,7 +130,7 @@ public abstract class SmoothPagedView extends PagedView {
         whichPage = Math.max(0, Math.min(whichPage, getChildCount() - 1));
 
         final int screenDelta = Math.max(1, Math.abs(whichPage - mCurrentPage));
-        final int newX = getChildOffset(whichPage) - getRelativeChildOffset(whichPage);
+        final int newX = getScrollForPage(whichPage);
         final int delta = newX - mUnboundedScrollX;
         int duration = (screenDelta + 1) * 100;