Upgrade streetview preview from static image to actual panorama

[alpha-beta-soup]

• https://developers.google.com/maps/documentation/javascript/3.exp/reference#StreetViewPanorama
• http://gis.stackexchange.com/questions/133878/working-out-street-view-heading
• https://developers.google.com/maps/documentation/javascript/examples/streetview-custom-tiles

Go from this (using static image API)...

...to the interactive version of this (using panorama tiles):

Probably should stick with only the static preview for small devices.

At present the static image API is used to position the viewport so it is facing the given crash location. However often this results in the view from the centre of the road looking at a building. Users can go to streetview by clicking on the image, but it would be easier just to allow camera manipulation inside the popup.