Rework the test suite and first modifications of the implementation

Related Eclipse Bug:
[418563 - support for Asciidoc](https://bugs.eclipse.org/bugs/show_bug.cgi?id=418563)


The copy paste approach you choose allows having some quick results, but when you look in detail Asciidoc and Markdown are not so close.

I started by rewriting the current test suite to have tests that are OK with the java-asciidoctor approach.

Implement AsciidocLanguageTestBase like this:

	public String parseToHtml(String markup) {
		Asciidoctor asciidoctor = Factory.create();
		String rendered = asciidoctor.render(markup, Collections.<String,Object>emptyMap());
		return rendered;
	}

And all the tests should be green. I started to make some modifications to the Asciidoc-Wikitext implementation to have also green tests (I commented with a FIXME the tests that are not OK with Wikitext).

Next step is to remove the Markdown behavior in the Asciidoc-Wikitext implementation (coming from the copy-paste), and to continue the implementation of the missing parts.

In my opinion: implementing the tests in order to have them pass with both renderers (Wikitext and Asciidoctor) is the correct approach. It requires introducing certain flexibility in the assertions, but it ensures that both implementations stays close enough.