Adds semantic bundle configuration and test helper classes
This release brings a new, semantic bundle configuration that makes shortcode definitions more concise (#21).
In addition to that, we have added a few helper classes and some documentation in the README that explains how you could test your shortcode handler implementations and the configuration/usage of this bundle (#23).
Through these two PRs, the README file has undergone a major overhaul, so you might want to re-read it to familiarize yourself with the new features.