Generate map markers, rectangles, and popups from search results

For the set of Browse Locations results, each geoLocationPoint is
turned into a map Marker, each geoLocationBox is turned into a
rectangle, and each map layer is given a popup box with information
from its associated metadata record.
Add links and buttons to the geographic interface

The Dash front page and the Browse All page both now have buttons
which are linked to the Browse Locations page. The records' pages
also have buttons if they have geographic metadata - eventually
these will link to a map with record-specific geoLocations. For
now the button links to the Browse Locations page too.