Authorbox relies on [Author] configuration, but it's being deprecated. #382

The code in the authorbox assumes that "Author" data comes from the hugo.toml configuration. When I add that configuration to Hugo I get the following warning:

WARN  The author key in site configuration is deprecated. Use params.author.name instead.                                                                                                                                                   

Furthermore, it'd be nice to support multiple authors.

I'll submit a PR to that effect.