adding dataframe explorer

should be fairly well documented and tested at this point - basically from the notebook call dframe_explorer.start with the right parameters and you can then go to a web browser and see leaflet maps (make sure to have a geojson file in your data directory in order to use)
bottle is now a dependency
include html templates as package_data
Merge pull request #69 from synthicity/add-dframe-explorer

adding dataframe explorer