List::Util is no longer being used
test both list and scalar context of ->authors
why use Sub::Install? I don't know what I was thinking!
use gravatars as configured on metacpan, rather than asking Acme::CPANAuthors

This fixes a few erroneous images in the pod (NMELNICK, BENW)
add "avatar_url" interface
Acme-CPANAuthors-Nonhuman-0.019

          - fix a few gravatars in html documentation by using gravatars as
            configured on metacpan, rather than asking Acme::CPANAuthors
          - add "avatar_url" method, for returning the metacpan gravatar (as
            compared to the old result from Acme::CPANAuthors->avatar_url)