Support for New Additions Since Last Update

[Peardian]

This is not a completely comprehensive update, but it adds support for many of the new fields (and a new action) that have been added to the API since the version 1.3 release. Support for the following features were added:

• SAFE-T Reimbursement financial events in Finance Core (Method for finance event report #127)
• Label format, label customization, and hazmat in Merchant Core
• Payment details and more buyer info Orders Core
• Product Fees Estimate action in Products Core (Action GetMyFeesEstimate not implemented #92)
• Return Items and Return Authorizations in Outbound Core

If I notice any more newly-added fields, I will add them here.

[Peardian]

I'm going to put the updates to the Inbound core in a separate pull request, possibly after the next version release.