*.manifest files should have a mime-type of "text/cache-manifest"

I realize that we can control the mime-types via .htaccess if we're using webfaction's Apache static app, but there's no reason this shouldn't be supported on webfaction's Nginx (no .htaccess) static app. It really should return a mime-type of "text/cache-manifest" for all files with the ".manifest" extension. This is part of the HTML5 Offline Applications spec (http://www.w3.org/TR/offline-webapps/), is critical for making a webapp work offline, and is supported by a bunch of browsers -- but only if it is served with the right mime-type.

I had already setup my own Nginx custom app (as a reverse proxy), so I'll just move it (and the rest of my static stuff) over to that, but it would have been nice to keep it on webfaction's Nginx static (no .htaccess) app.