Fixed log levels of configuration parsing errors. All the errors that prevent loading configuration must be printed on the "emerg" log level. Previously, nginx might silently fail to load configuration in some cases as the default log level is "error".

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