Show that sibling explosion exists and is trivially easy to produce

The idea is to now fix this using a DVV like scheme
Update test to match non-explosive expectations (ie DVV)
Added docs as per reviewer request
Add test for sibling explosion and DVV

With DVV the test passes, wthout the cluster B results are...
explosivey. Non-deterministically high number of siblngs
(assuming as it takes a few moments for rt repl to work.)
e
Added comments, cleaned code a little
Merge pull request #480 from basho/bug/rdb/sibling-explosion

Add tests for sibling explosion resolution with DVV