Implement cluster CLI commands

Implement the following commands using riak_cli:

* cluster status (improved member-status)
* partition-count
* partitions
* partition id=\<id\>
* partition index=\<index\>
* members

TODO: After merge, some code clean up and boundary checking.

Depends on basho/riak_ee#295
This is totally a bikeshed comment and won't hold up a +1 of this PR. I was just thinking that we should align this better. Either put the (c) after the Node name, since it's left aligned, or  put 3 spaces before the non-claimant nodes so it is right - aligned.