Use systemui's applied theme for notifications.

Notifications contain RemoteViews which are inflated using the
application's context for which this notification belongs to.  This
can look out of place if SystemUI is using a different theme than the
rest of the system.

This patch will use SystemUIs theme when inflating the RemoteViews,
giving us a more consistent look in the notification drawer.

Change-Id: I9514ce7fcc4858bad3d3c4190f55c1f5a1441d7c