upgrade browserify to 6.1.0
but we need a new release of es6ify before we want to merge this upgrade
Tile class work
Test some interactions between the Scene object and the Tile object
Pass the TileSource to the Tile object
Move over zoom calculation to tile source
Issue with Object.assign overriding values on Tile Object
Remove method
Fix tests
Fix broken leaftlet tests, move TileSource construction to create method
Back off some tests
Fix rebase
Fix tests
Add worker test back
move bounds calculation into Scene (no need to set it explicitly anymore)
update tests to match
Merge branch 'master' into bounds
upgrade jshint
Merge branch 'master' into upgrade-browserify
upgrade es6ify
Merge pull request #39 from tangrams/upgrade-browserify

Upgrade browserify to 6.1.0
merge master & update tests