Pimping up packaging script

Summary:
Moved everything into one file. This makes interoperability more painless. No wrong file name, false url, etc.

Uses new `packager.register` Conduit method.

Also enabled logging. It always tries to put a big huge JSON blob into S3. Hope it works.

Refs T166

Test Plan: not yet

Reviewers: anh-chrome

Reviewed By: anh-chrome

Maniphest Tasks: T166

Differential Revision: http://phabricator.burningreality.de/D125