Feature/revised/riak cli handoff status 1239

Implement "riak-admin handoff summary" and "riak-admin handoff details [--node=<node>] [--all]"
I think I did that because I had once seen a literal duplicate in active transfers somewhere, but perhaps I was hallucinating, as I wasn't crazy about it either. I'll try to remove it and do some testing to see what's up, but you really should never have a duplicate active transfer from what I can tell.