Map improvements

New colors added, poplar and willow data added, maps tab removed in favor of model I/O -> model projections.

Possible future improvements: 
'download current' button
Fix certain counties not appearing above a certain zoom level (they exist, but fusion tables won't render more than a thousand polygons without trimming all below a certain size. Prototyped making each crop layer three fusion tables layers each of ~900 counties, could work.)