Add `main` to `package.json` for webpack
Add `main` to `package.json` for webpack

This way, we can `npm install` dimple, and use `require('dimple')` to pull it in webpack.
zhangweiabc/dimple,PMSI-AlignAlytics/dimple,PMSI-AlignAlytics/dimple,sjtg/dimple,bbirand/dimple,upsight/dimple,confile/dimple,mlzummo/dimple,mlzummo/dimple,bbirand/dimple,upsight/dimple,confile/dimple,zhangweiabc/dimple,sjtg/dimple