make main module a POD document for now

The Curator system will probably have no single entry point, since
it will be a more a set of tools, each with their own manner of
usage.
add build artifacts for documentation and contribution

Keeping {Build,Makefile}.PL in the repo root makes it easier for
people to contribute (no need to install Dist::Zilla).

Keeping LICENSE, README, and README.mkdn make it easier to see
these important documents on the Github page.