hardwired setting, should be a config variable).  If experiment swapper is
an admin, only admin homedirs are exported to the experiment nodes.  If
swapper is not an admin, only non-admin homedirs are exported.

This is really a half-assed measure, stopping short of requiring that projects
have only admin or non-admin users.  If we take that step, this code won't
be needed.

Also, sort list of nodes by increasing IP address (w00t!)  Helps make the
output more predictable for diffs.