PUT to cluster send to all nodes rather than none

PUT to cluster send to all nodes rather than none

If the location log says all nodes contain content, pass in all nodes,
rather than none.

The location log can be wrong. While it's good to avoid unncessessary
connections to nodes that already contain a key, it would be bad to
refuse to accept an upload at all when the location log is wrong.

Also, passing in no nodes leaves the proxy in an untenable state. It
can't proxy to no nodes. So it closes the connection. Passing in all
nodes means it has to do the work to connect to all of them, and see
that they say they already have the content, and then it can tell the
client that.