Add basic redirect support

[stianst]

Signed-off-by: stianst [email protected]

[ahus1]

The concept looks good to me. I might consider inlining resources/redirects into the HTML using freemarker logic to avoid another remote request.

If we have a match, I updated the page title so that Google Analytics will record something different than the page title "page not found", as we use that in our report. See stianst#1 for a PR. Inlining would still make sure that this update doesn't happen too late.

Instead of startWith() I would instead prefer a RegEx as we would soon use wildcards for version placeholders (redirecting to the latest version if a earlier patch release was removed), or having a wildcard for with and without .html.
If you think this could be handled in a follow-up PR, feel free to merge this one.