Commit 95786e5 made swift-get-nodes only output N handoff nodes, where
N is the ring's replica count. This change leaves that behavior in
place as the default, but adds the option -a/--all to print all the
handoff nodes.
This is handy if you're consuming the output with a script, e.g. if
you're doing some analysis of the distribution of primary+handoff
nodes for a particular set of things.
Change-Id: Ie0253575bb21ccf25559a1c5fd20570a58a2d9fa