Active display: Enable proximity sensor only when screen is OFF
Active display: Use a default notificaiton icon.

In case there is an exception when trying to load the
notification icon we will use a default one.

Change-Id: I4087ef3e407cf976f7bfb2bb89f850641101bc73
Active display: Only fetch next notification if mNotification is null.

Change-Id: Ife8511d4a4b8c448bc7aa8997a250068bec5fae7