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
I don't really like the `\t` here. I prefer things left-aligned. Even if you put the id on the next line with the owner it would work left-aligned. I will open this bikeshed up to @macintux @aberghage.

Currently output looks like this:
```
Andrews-MacBook-Pro:riak_ee ajs$ dev/dev1/bin/riak-admin cluster partition id=38
Partition id: 38 -> index: 867766597165223607683437869425293042920709947392
	(owner: 'dev2@127.0.0.1')
```