Updated webpack config and webpack versions

[LOLdevelopr]

Updated the wepack-cli and webpack to new version In webpack.config.js added splitChunk and uglify plugin for optimizer.

[facebook-github-bot]

Thank you for your pull request and welcome to our community. We require contributors to sign our Contributor License Agreement, and we don't seem to have you on file. In order for us to review and merge your code, please sign up at https://code.facebook.com/cla. If you are contributing on behalf of someone else (eg your employer), the individual CLA may not be sufficient and your employer may need the corporate CLA signed.

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[LOLdevelopr]

I have already signed the CLA for facebook . I dont know why its not showing