The API doc is incomplete.
The package/upload endpoint expects a multipart post, containing a name parameter containing the desired package name and a file parameter containing the package file.
File a support ticket. I already did. Answer was that it would not be solved in the next half year. And indeed the documentation is incomplete. Also a support ticket for that because I need answers first before I can adjust the documentation. I need to know if my assumptions are correct.
Hopefully when more users file a ticket that the current deployment API is useless (it also will not work in the V4 cloud) this issue get's a bit more priority.
Regards,
Ronald