Added variables support to server_tokens. It can now be set to "off" conditionally, e.g. using the map directive. An empty value will disable the emission of the Server: header and the signature in error messages generated by nginx. Any other value is treated as "on", meaning that full nginx version is emitted in the Server: header and error messages generated by nginx.

au BufRead,BufNewFile *.nginx set ft=nginx
au BufRead,BufNewFile */etc/nginx/* set ft=nginx
au BufRead,BufNewFile */usr/local/nginx/conf/* set ft=nginx
au BufRead,BufNewFile nginx.conf set ft=nginx