Refactoring folder content

> Refactoring the CellLayout in folder with a custom view so
that it can be replaced easily with a scrollable paged view.
> Moving some methods from the folder to this new view which
assume a single page layout for the folder
> Changing folder from LinearLayout to FrameLayout to properly
handle focus traversal in case of multi-page folders

Change-Id: I073c00b995488f9f5d8123b00357e094ca2cec7c