Ignore hard line wrappings in Markdown.

Github Flavoured Markdown changes from the Markdown standard in that hard
newlines result in <br /> tags being inserted in the HTML output. This
effectively prevents raw Markdown files from being wrapped at a certain line
length. This in turn makes it impossible to read these files in their raw form,
which contradicts part of the use case of Markdown.

To solve this, one can do the following:

1. Stop using Github Flavoured Markdown
2. Unwrap all Markdown files
3. Tell Kramdown to not care about line wrappings

In this case I went with option 3. Although option 2 has already been applied
this means we can, over time, re-wrap files where needed without it affecting
the end HTML output of this website.

More information about the parser options of Kramdown's GFM parser can be found
here: <http://kramdown.gettalong.org/parser/gfm.html>.