Add attribution/copyright fields to reports

[aCandidMind]

Hi,

thanks for this great gem. Currently there's the author column which is a good thing to have. But in our reports we have to post the attributions/copyright line. Currently this is a semi-manual process for us.

The licensee gem has a matcher that seems to work well.

It would be great to have this as a report column in license_finder.

[annania]

I am also interested in copyright/attribution.