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
So, I clearly need to write better docs as I've learned the last couple days. Errors should actually be wrapped in alerts. That way, eventually, we can bold or make them red, etc... We also can build separate error csv files.