middleware: Add 'symbolLayerMiddleware' API (#39) (4320452)
You can now provide a symbolLayerMiddleware function which allows you to modify each layer before it's added to a symbol. Most notably, this will allow you to set resizing constraints via html-sketchapp's new setResizingConstraint API.
deps: Update html-sketchapp to v3.x (#38) (4d9547c)
The install command now downloads the Sketch plugin from html-sketchapp's GitHub releases, since it's no longer published to npm.