Several improvements to RecentActivities:

It now toggles between show/hide for each tap on the home button.

Added new bitmap generation for lighting and halo effect while loading.

Uses new CarouselViewHelper class to manage textures and threading.

Uses a "real view" to render detail text.

Activities can now overload onCreateDescription() to show a
description in Carousel.

Improved startup and resume speed by posting single event to
refresh the activity list.

Change-Id: Id5552da75b9d022d24f599d11358ddababc97006