Add back button support to nearby overlay and preview overlays (geonotahack)

* Overhaul page previews to be less hacky - this adds one api
request to a page preview (added FIXME to address this later)

Change-Id: I7ef13384bf1a100bb0aacf9dc5b57bd61e350871
Merge "Add back button support to nearby overlay and preview overlays (geonotahack)"