Ability to drag and drop geojson onto map with path / envelope information

[defiantgoat]

This is slightly related to #3

If a user has a geojson file (or an esri json) file with geometry information, then they should be able to drag it to the map and have the path drawn on to the map for them to use in order to export tiles.

References

• Current geojson spec: https://tools.ietf.org/html/rfc7946
• Esri's geojson conforms to a slightly older version of the geojson specification that includes a 'crs' parameter. Current geojson spec recommends that WGS84 always be the SR for interoperability.
  • An example of esri geojson
• GeoJSON tool > http://geojson.io/

[marikavertzonis]

tested build 1.0.97 on windows 10, mac 10.9.5 and ubuntu 14,
and successfully

• manually drew line and polygon features
• dragged and dropped a json file onto the map
• copy/pasted json from arcgis online feature service queries to the map
  in order to create a selection area for creating the TPK.