Copyright Creative Commons

This version includes patches from @vascoalramos and @b-pereira, to fix a bug in uminho version and add support for Creative Common licenses with:

\ntsetup{copyrightmodifier=MOD}

where MOD can take any of the following values: by-nc-sa, by-sa, by, by-nc, by-nd, by-nc-nd.
The default is: by-nc-sa