Allow ExamplesTable to be loaded from external resources

At times it may be convenient to load the content of an examples table from an external resource, be it from classpath or URL. The default resource loader will be the URL-based one as it does not require any additional configuration, unlike the classpath-based one that requires the class from which to derive the classloader.

The ExamplesTableConverter should be able to handle both cases (textual table input or resource path input) via the use of an ExamplesTableFactory.

The RegexStoryParser should also allow the use of the ExamplesTableFactory.