Enable rTorrent's log by default

Signed-off-by: kfei <kfei@kfei.net>
Add a wrapper script

1) Deal with runtime configurations from environment variables.
2) Move some code from rTorrent's `run` to the wrapper.
3) Add first run time configuration: `DKT_LOGS_OFF` which disables all
   logs from rTorrent, nginx and php5-fpm.

Signed-off-by: kfei <kfei@kfei.net>