Add an exhaustive test for AAE based replication.

Ensure that AAE replication is tested using all possible failure cases
when dealing with the riak_kv_index_hashtrees and failed connections.

First, use intercepts on riak_kv_vnode and riak_kv_index_hashtree to
ensure that we simulate errors on a per node basis, starting with the
source cluster and moving to the sink.  Simulate ownership transfers,
locked and incomplete hashtrees.  Verify partitions generate the correct
error count, after using a bounded set of retries, and finally remove
all intercepts and verify that the fullsync completes and all keys have
been migrated between the two clusters.