Ready: Riak CS Multibag docs

- [x] Command line docs in **Riak CS Command Line Tools**
- [x] Configuration in `app.config`
- [x] Architectural description
- [x] Stanchion configuration
- [x] Etc.
Is this "each" means a Riak cluster?

Precisely speaking, riak cs / stanchion do not belong to specific riak cluster.
Also they are not necessarily running on the same box (server) of riak.

Conceptual veiw (in my mind) is like this
(R is riak node. Connections from CS2, CS3, .. are ommitted for simplicity):

```

Stanchion -+   +------------------- bag-A ---------------------+
           |   |                                               |
           |   |   +-----------+              +-----------+    |
           +---|---|--R R R R  |              |           |    |
           |   |   |  Cluster  |--------------|  Cluster  |    |
CS1 ---+---|---|---|--R R R R  |              |           |    |
       |   |   |   +-----------+              +-----------+    |
CS2    |   |   |                                               |
       |   |   +-----------------------------------------------+
CS3    |   |
       |   |   +------------------- bag-B ---------------------+
CS4    |   |   |                                               |
.      |   |   |   +-----------+              +-----------+    |
.      |   +---|---|--R R R    |              |           |    |
.      |       |   |  Cluster  |--------------|  Cluster  |    |
       +-------|---|--R R R    |              |           |    |
               |   +-----------+              +-----------+    |
               |                                               |
               +-----------------------------------------------+

```