If _nginx_ is configured to send error/access log messages to syslog, it
may not make sense to _also_ send messages to log files as well. The
`nginx_error_log_file` and `nginx_access_log_file` variables are now
available to control whether/where to send log messages. Setting either
of these to a falsy value will disable logging to a file. A non-empty
string value is interpreted as the path to a log file. By default, the
existing behavior of logging to `/var/log/nginx/error.log` and
`/var/log/nginx/access.log` is preserved.
The default `logrotate` configuration for _nginx_ may not be appropriate
for high-volume servers. The `nginx_keep_num_logs` variable is now
available to control how many days of logs are kept.
