Generate default config at startup

[aslian]

Please make it so that app generate a config file with default values and place it in one of locations.

With current behavior, it's somewhat hard to realize what user needs to do in order to change the defaults and what the defaults are.

Example from README.md may be outdated and so on...

[nfx]

@aslian there's no central place for default configuration values, just in case. e.g. you don't have to create a full config to run the app, as for every unspecified value there'll be a default.

adding a "setup" experience is definitely an interesting idea.