create example data inputs for FV-11

[jordansread]

• the bounding box (lat/lon)
• the map projection
• list of gage IDs
• size and aspect ratio of image
• reference places would come from geojson (e.g., city names and locations to display; major river features)

[jordansread]

library(geojsonio)
geo.out <- us_cities[us_cities$name %in% c('Des Moines IA','Cedar Rapids IA'),]
geojson_write(geojson_json(geo.out), file = '../flood_cities_01.json')