[BUG] applied changes during puppet run show empty on puppetboard if containing xml

[hbzf1]

When puppetboard is used to display the applied config file changes, the output will show empty if it contains xml. This is because the xml output is being treated as part of the html content, which causes them to not appear, as there are no html tags that use the naming of the xml document. If you view the html source, you can see the xml was added to the html page but unable to render because it's treated as html:

Output in browser:

Output in html:

[mathiasaerts]

Related to #865