Feature/revised/riak cli handoff status 1239

Implement "riak-admin handoff summary" and "riak-admin handoff details [--node=<node>] [--all]"
I'm wondering if we could make this type spec shorter, if only for the sake of readability. Could we, say, define an intermediate type or two to encapsulate some things? I suppose this is getting a little nitpicky though, so feel free to disagree and/or ignore my comments in this case.