Port AAE Updates

Since the initial introduction of AAE to Yokozuna several updates have been made to KV AAE from which it was derived (i.e. YZ AAE is basically a copy/paste/modify).  The following commits, where applicable, should be retrofitted to Yokozuna AAE).

* basho/riak_kv@691dad2b6724cb24211409777a20d7c0a00724d2

* basho/riak_kv@6b5a85e619e81255f35853038bac14ef58c3964b

* basho/riak_kv@1a8c3de16da4c31e311d0afa781c863e161fd261

* basho/riak_kv@bca3801acacbf0329db99bae5ddcdffc660896d1