Metadata and doc improvements

Hi Jakob,

I've made a number of small changes to follow conventions for metadata and pod:

* Added abstract (=head1 NAME). MetaCPAN wasn't finding an abstract for the module, which means it
  presents the module slightly differently from other modules.
* Added author and license/copyright details to pod
* Added [AutoPrereqs] to dist.ini, so Makefile.PL will list the prereqs

Cheers,
Neil