added plantings, seeds, and harvests to the crops JSON
Add map, move info to sidebar
Tweak what's emitted as JSON

(let's just emit plantings for now, as that's all we're using)
Display crop plantings on a map
Reduced cluster radius for maps

on both crops and places pages

Did this because the clusters were annoyingly over-general, eg. showing
164 people in the eastern part of North America.  Cluster radius of 20px
is about the radius of the cluster icon itself.  Seems to work better
eg. for separating Melbourne from Sydney on the world map.
rearranged crop page headings and added tests
Merge pull request #361 from Skud/crop-map

Crop map