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.
* Adds step-after functionality, true defaults to step-before
* Update stepped line sample to include all variations of steppedLine configurations
* Update documentation on steppedLine values
* Add tests for new steppedLine values 'before' and 'after'