Set the prefix properly
Remove a debug log
Add debug logs to tar

It also serves as a progress meter on the server
Fix crash in timeouts in libwire
Close the request side of docket client

This lets the server know we are done with out requests and it doesn't
need to rely on its stdin timeout.
Reset timeouts in docket client
Add debug logs to docket client

It also serves as some sort of a progress meter.
Only zero bytes we really need to send

Sometimes our buffers can be very large and the number of zeroes to send
is very small. No need to touch all bytes.
Correct the function header
Only read and write as much as needed

If the file was growing in size we could send more data than we said we
will and that completely messed up with the tar file format. We need to
send no more than we promised.