Fixes #1 broken tests

Changes the test so it doesn't use the generation of h1...h6 tags, but just a plain paragraph.

That way, we avoid to test the generation of tag ids that became a default on a newer version of [marked](https://github.com/chjj/marked) for h1...h6 tags.
Merge pull request #3 from fegemo/broken-tests-fix

Fixes #1 broken tests