Add drop animation / Toast to widgettray

- show instruction toast on clicking the widget
- Add animation when widget drops on the workspace.
Added WidgetHostViewLoader to handle short press and assign widget
host view to enable animation

b/19897708

Change-Id: Iec36d72cb21bf09343d0beeb31a09bf8b0cb5e0d

src/com/android/launcher3/AppWidgetResizeFrame.java

@@ -349,7 +349,7 @@ public class AppWidgetResizeFrame extends FrameLayout {
                 mTmpRect.right, mTmpRect.bottom);
     }
 
-    static Rect getWidgetSizeRanges(Launcher launcher, int spanX, int spanY, Rect rect) {
+    public static Rect getWidgetSizeRanges(Launcher launcher, int spanX, int spanY, Rect rect) {
         if (rect == null) {
             rect = new Rect();
         }