* upgrade leaflet modules to 1.x latest
* fix css for leaflet controls
* update draw options so it is easier to see polygon when drawing
* fix chrome touch issues with closing polygon in leaflet draw
* use canvas renderer
* use leaflet-responsive-popup to avoid tooltip cutoff
* remove radius configuration from leaflet heatmap
* make blur a factor of radius. Set maxZoom to map zoom since new values are calculated per precision
* use _.get to avoid error, cannot read property of undefined
* add cluster size slider
* experiments with image differences
* onload not onLoad
* use canvas dimensions
* compare map canvas to stored PNG of map canvas
* remove pixelmatch from project dependecies
* fix broken test - rounding error
* add expected image tests for geohash layers shaded circles and geohash grids
* bump z-index of vis-spy
* update functional test expected data
* update to leaflet 1.2.0
* revert to leaflet 1.0.3 and update expected data set for map functional tests
* test geohash_layer heatmap in unit test
* update region_map functional test since it can not longer pluck map vectors from DOM
* update documentation
