add "email alias" functionality

We now look through a list of known alternate email addresses for
authors, to map them back to one "canonical" address.  This is
mainly to make metacpan's job easier, w.r.t. figuring out what CPAN
authors contributed to the dist by allowing people to map their
other addresses back to their xxx@cpan.org address.

Right now, this list only includes me :)  Pull requests are highly
encouraged if you'd like to add to this!
dzil: autoadd cpanfile
add author-mapping tests

I know, I know...
v0.007

	* add support for author email mapping