Changes for dump/restore users:

* dumpuser: Change some user table fields to optional, since Portal
  users do not have to fill those things out (address, phone, zip,
  etc). I am using this to transfer accounts from the Mothership to
  inner Emulab when CONFIG_ADMINUSERS=1.

* newuser: equiv changes, allow some fields to be optional that usually
  are not. Also allow the password has to come through, normally we do
  not pass that through.