[Feature] --excludeScopes option

[ChrisHubinger]

In our Project wie have a private NPM registry and internal scope where lots of the packages are not licensed correctly, which is fine for us, but with the need to license check all 3rd Party code we are using this became a problem. I've found no option to make license-checker simply ignore those packages without the need to maintain an explicit list of package@version to exclude.

To fix my issue I implemented a --excludeScopes options (see: https://github.com/davglass/license-checker/pull/219). I'd be very happy if this woould make it in the next release version so that we can start to use it in out project.

kind regards & thanks for the great work you've done with this tool

Christian