Add a basic map page to display the result of location searches

Add a basic map page to display the result of location searches

After a fair bit of playing around and reading of licensing agreements, it
seems like the easiest way of getting a useful map, a good geocoder and being
able to style things to look how we want is to use Google Maps. The usage
limits (25,000 map requests, 2500 geocode requests) are unlikely to cause a
problem for this application currently, and the licensing agreements don't
look like they'll cause any grave issues for us or the data.

Closes #9

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