[2.0.1 Documentation] 2.0 REST API changes need to be documented

We've made some changes. Most notably we've added new stats requests. It needs to be documented.

Moved from MB-6858:

I'm filing this as a major bug, as the REST api documentation lacks a walkthrough regarding how to perform common operations.

The Web UI exposes the following operations (current as of 2.0-beta):

* Creating a new bucket [ram quota and all ] - mostly covered in the REST API

* Modifying a bucket [ covered ]

* Failing over a node: This is not clearly covered - there is documentation for failover, eject, and rebalance but it is not clear from the documentation that these three operations are likely to be used in conjunction with each other.

* Adding a node: Document clearly how to add a node to a cluster by contacting the to-be-joined node. Also there is a 'addNode' function which doesn't seem to be documented - if this is public API it should be documented as a way to join a node to a cluster by contacting the cluster

* Rebalancing the cluster. Clarify the use of 'otpNode' parameters, what exactly belongs in the ejectedNodes parameters etc. (show examples with adding and removing nodes). Also show a clear example of polling for the rebalance to complete.

* Compaction: not documented at all

* Bucket/Node statistics. It would be nice to document these ('self-documenting fields' -- self-documenting for who?)

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All of the examples which require multiple steps (or involve performing other requests in order to obtain requisite information) should be demonstrated using a real programming language (not curl). Perl or Python are languages which expose a fairly simple HTTP interface) and through which examples may be scripted and are both common languages used for system administration.