Add ability to report wrong link

[bartoszmajsak]

It would be handy to give the user an easy way to report that given URL is broken.

On 404 page we can dynamically generate a link which will result in new issue created in GitHub.

https://github.com/arquillian/arquillian.github.com/issues/new?title=URL_ENCODED_TITLE&body=URL_ENCODED_MESSAGE

We can use simple templates to prefill both title and the issue description.

Where title could be:

Wrong URL {window.location.href}

And message:

When accessing {window.location.href}, 404 is shown instead.

Please provide more details how you found this link

When passing using github url provided above, both texts should be URL encoded.