Mw read reapair reduced n test

The intent of the new test is to demonstrate read-reapir and reduced-n replication play well together.

New test is repl_reduced:read_repair_interaction

Two OS env or config file options:

* SKIP_TEARDOWN skips the eunit teardown of the clusters so they can be inspected. If the test passes, however, riak_test will still tear them down. Defaults to false.
* FILL_SIZE is how many objects to fill in during the large test. Defaults to 1000.

The test indicates data is as expected on the cluster. Reviewer should ensure this is really testing what we expect. If it is, the chatty-ness can be greatly reduced.