Merge pull request #112 from patrickarlt/master

Feature grids and clustering!
Merge pull request #114 from patrickarlt/master

Small fixes and fixes to build process.
Merge pull request #115 from patrickarlt/master

switch back to tile w/h based padding
Merge branch 'master' of github.com:Esri/esri-leaflet
fix alignment of clusters
fix removing cluster layer from map, allow use of default cluster
fix inaccurate boundsToEnvelope helper