[feature] command to 'add' from remote sources

[kiwiroy]

Idea

Add a new command, or augment add to download a release from GitHub/Other.

In the case of GitHub something simple like:

opan add shadowcat-mst/[email protected]

would download the asset from the v0.003002 release and opan add the file.

For a URL (bad example OPAN_MIRROR=http://backpan.perl.org already does this):

opan add http://backpan.perl.org/authors/id/S/SR/SRI/Bundle-Catalyst-0.01.tar.gz

would likewise just download the asset and add it.

It would require that the release was a dist/build artefact rather than just an automatically generated tarball from a tag.