Obnam: client for server

Goal My goal for today is to write client-side code to use the server HTTP API to store chunks. I'll want the client to be able put and get chunks, find chunks by label, and delete chunks. Plan Add obnam api put CHUNKID LABEL --file FILE to upload a file as a chunk. Add obnam api get CHUNKID --output FILE to download a chunk and store it in a file. Add obnam api find LABEL to list IDs of chunks…