Update Of New Extensions-Templates-Repository Test-Site

I updated the test-website for the new LibreOffice extensions and templates repository with my latest developments today. I worked on four additional validators and fixed some issues in the view templates for the content. I added also a new theming add-on, based on the default Plone 5 theming product, named Barceloneta. The test-site is available at http://vm141.documentfoundation.org:9090/liboexttempsite.