Create markdown parser service

Adds a markdown parser service which can convert markdown into plain html through the use of flexmark. (This may require a license update but I'm no expert on this ) Their license can be found here: https://github.com/vsch/flexmark-java/blob/master/LICENSE.txt

th:utext="${@markDownParser.parseToHtml(markdownText)}" can be used in order to convert markdown into html where makrdownText is the text to be converted.

merged