[COOK-3672] Add gzip_static option

https://tickets.opscode.com/browse/COOK-3672

Nginx with on-the-fly Gzip compression does not pass the Content-Length: header, which
is used by CloudFront and other CDN's to determine whether a file has been fully received.

Modify the recipe to support the gzip_static option so that precompressed Gzip files can
be used, which doesn't cause htis problem.