expires.conf: remove duplicate .ico cache headers
Don't cache .html or .htm files

Thanks @aitte, ref #133
nginx: change regex patterns to non-capturing for speedup
protect-system-files.conf: use "deny all" for clearer intent when blocking access
nginx.conf: Remove the gzip_buffers directive and let nginx figure it out instead, that way it will align them to CPU cache lines for greater performance
nginx.conf: Make use of the "auto" directive to let nginx spawn as many workers as there are CPU cores
replacing everything with more descriptive comments

for people that don't know what the options do
nginx.conf: protect server against the BEAST SSL attack (ref: http://nginx.org/en/docs/http/configuring_https_servers.html)
nginx.conf: Massively speed up SSL connections by caching the sessions for 10 minutes rather than constantly re-negotiating
nginx.conf: Add support for default SSL certificate served to clients with old browsers
cache-file-descriptors.conf: new feature which greatly speeds up performance on very busy production sites
protect-system-files.conf: clarify why people should be using it