client: update to new Packer interface and DirEntry struct
client: update to new Packer interface and DirEntry struct

Change-Id: I8243e633a23a164690588e73208453c4836f867b
Reviewed-on: https://upspin-review.googlesource.com/2743
Reviewed-by: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@google.com>

upspin/upspin,upspin/upspin