Add replication2_upgrade test

WARNING: >> THIS TEST DOES NOT ALWAYS PASS YET <<

This test is just like replication_upgrade, except that it is targeted for upgrades from 1.3 to 1.3.1 or 1.4 or anything similar. It assumes the Brave New World replication system and only tests that system.

Please also include the replication PR: https://github.com/basho/riak_repl/pull/219, which is required for this test to maybe pass.

NOTE: The replication2 test now passes. However, the replication2_upgrade test fails more often than it succeeds. This is due to a failure of the cluster manager to reconnect after it's connected peer is upgraded. I don't think it has anything to do with the upgrade, really. The test hangs while waiting for the clusters to be "connected", which never happens. This usually occurs when the second of the three remote "B" nodes is upgraded. This appears unrelated to binary objects and is almost certainly a cluster manager issue, which I will address after we ship 1.3.1.