Samples are supposed to show good practices and in most cases we don't use the time scale but require `Chart.bundle.js`, which is not correct. Instead, we should require the non-bundled version in its minified version (`Chart.min.js`). Paradoxically, time based examples don't use `Chart.bundle.js` but require moment manually side to `Chart.min.js`, which IMO is also the correct way since it allows users to configure and use moment globally (TZ, locales, etc.) and doesn't enforce a specific moment version.
Also remove the `data-labelling.html` example because we now have an [official plugin](https://github.com/chartjs/chartjs-plugin-datalabels) that implements this feature and don't want to deal with user custom code anymore.
Inject the GA tracking snippet for all samples, including the index page. Also update README.md badges using the shields.io service for consistency with flat-square style and cache, and add release badges to the installation documentation page.