resolves #4623 

* Use latest for all examples

* Update yarn.lock

- tackles #997
- add ./idea to gitignore for webstorm users
- update all the examples

* Added universal configuration example

* Make example more clear

* Added data fetch example

* Finished updating examples install instructions and added data-fetch example to main readme

* Immplement the initial singleton Router.

* Use the new SingletonRouter for HMR error handling.

* Use SingletonRouter inside the Link.

* Create an example app using the Router.

* Make the url parameter optional in Router.push and Router.replace

* Add a section about next/router in the README.

* Remove the use of CDN and bundle everything inside the app.
We still pre-build the prefetcher because it needs
different webpack config which only targets browsers
supports Service Workers.

* Remove cdn config item.
We no longer using it.

* Stop adding script tags when staticMarkup=true

* Remove babel-plugin-transform-remove-strict-mode NPM module.

Earlier we add a event to init next.js when dom has loaded.
But if at that time dom is already loaded, next.js won't get init ever.
Now we are using domready NPM module which handle these for us.

* Add example app which demonstrate the problem.

* Add the first working version.

* Fix lint issues.

* Add README.md

* Use /_next/main.js as the main file URI

* Add the support for loading the core next bundle.

* Optimize the output by removing Next modules from pages.

* Use the same package.json as master use.

* Change the example repo's README for simpler instructions.

* Change example projects package.json to support next build and start.

* Change main.js into commons.js.

* Add support for hot core reload and errors.

* Introduce require based on eval-script.

* Add error reporting support with hot reloading.

* Update README.md