Replace `release.php` with a set of static links updated upon release

[theseer]

The release redirect is powered by a small PHP script which connects to the Github API to find the latest release and redirect to the appropriate asset.

Performing such an API call to github.com upon every request is a hack, particularly since the current release information doesn't change very often.

The links to the asset files associated with a release are static.
So instead of calling the API, we should create the redirects statically upon release.

[theseer]

Note to self: The link redirect is now within NGINX. A new release should still update this.