allow auto generated config file to use options given at runtime

[aussielunix]

Given my app makes use of app.config_file ".foo", :autocreate => true
Then when I invoke the app with foo --no-daemonize -d dbname -u dbuser
I would expect the config file to be generated with the data supplied.
Instead I get a config file with the default data that is hard coded into the app.

The above would let the consumer of my application build out a config file with ease.