Native support for transaction bundles

[vadi2]

Some servers (such as HAPI) enforce referential integrity by default, requiring you to either upload resources in the right order, or to use a transaction bundle to do the upload. While there is a documented way to export all data to a transaction bundle and then upload it, it would be nice if there was just a single CLI flag that would do this all for you.

[brianpos]

I decided to go the other way on this one as the per resource process actually does diffs against the existing content on the server so it doesn't update content that hasn't changed, and uses existing IDs without needing the bundle/transaction processing.

The bundle that it produces has been re-ordered to ensure that resource dependencies are considered. It does also check for circular dependencies, so it doesn't break - but it minimizes things.