allow to work without config

[tshepang]

This tool works well with an empty config, so should not fail when it does not exist.

Alternatively, on first use, you can prompt for those settings.

[ubnt-intrepid]

Thanks for reporting the issue (and sorry that the reply was delayed).

It is a better idea to prompt to build initial settings if the configuration does not exist. I would like to think about detailed specification until the next release.