* add null check for children and extract

* update null check for children and extract

- Move lifecycle methods on top
- Handle null nodes inside MetaTag

Unmount temporary meta tags element on MetaTags component unmount

- Code refactor of server utils to remove duplicate.
- Change deserver port to 9010 for examples webpack dev server

- Added npmignore

- Upgraded to babel 7
- Upgraded to webpack 4
- Use rollup to create smaller bundle
- Removed babel-runtime

- Fixed readme

Create LICENSE

- Use babel transform runtime so build size is smaller

Dear developer
for a better license recognition I would like to add a `LICENSE` file which contains your license (MIT).
The reason behind this is that people hesitate to use your work in production because it only contains a header in distributed files but no separate license file which fully supplies the MIT license which might cause legal issues.

- Separated prop-types from react package
- Only transpile src to lib. Avoid creating bundle. This will reduce app bundle size.
- Fixed example to run on dev env (Webpack configuration needs to be fixed)

Upgrade peer dependency to react 16