* Rename elements to mark as elements, i.e. Arc -> ArcElement
* Rename RectangleElement to BarElement
* Also updates options.elements.rectangle to options.elements.bar
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.
The bar `backgroundColor`, `borderColor`, `borderWidth` and `borderSkipped` options are now scriptable (unit tests, docs and a basic sample). Also fix the gulp task that generates the documentation on Windows.
