Some browsers, such as Firefox 53.0 try to download the specified file,
to improve development experience. Since we don't host this file, some
users were making a request resulting in 404 when loading the page in
Fixes issue #42
Also adds logic for private torrents requiring site tracker as the main tracker (otherwise there's no point on uploading them on the site)
Changes upload.html wording to reflect the requirement to have the tracker, not necessarily as the first one.
These changes add a macro that creates the relevant HTML markup for a
markdown editor. In the main.js file, we bind the relevant elements with
the marked library, so users can see their contents in a HTML format.