User:Clouserw/Builder/upgrading

The decision was made that only add-ons from builder.addons.mozilla.org should be able to be automatically upgraded on AMO. Steps to get there:

- Adjust SDK to allow us to send the builder key/value in package.json - Add builder identifier to package.json - AMO should pick up on the builder identifier in the package.json - AMO should only send "builder" add-ons to be repacked via the admin tool - AMO should only send the necessary data to builder (no longer the file URL) - Builder should only require the necessary data from AMO (no longer the file URL) - Builder should use its knowledge of the add-on to build a new package instead of trying to repack one that AMO sends