Add whitelisting parameter to CLI

[dawedawe]

Is your feature request related to a problem? Please describe.
Currently, it's only possible to ignore files with a pattern when using the CLI. For CI stuff it would be nice to have a whitelisting parameter in the CLI

Describe the solution you'd like
Add a whitelisting parameter to the CLI.

Describe alternatives you've considered
Sure, the ignore pattern can be used to get something like the requestet feature. But it's just harder then it needs to be.

P.S. Of course, I don't expect other people to do this work for me. It's more a note to myself, to keep track.

[dawedawe]

Implemented in #196