Revert "Remove riak_kv and ibrowse from deps"

This reverts commit 1a95c25d80d3ab90a06c62b1be66fc8cf26a5dbe.

I'm reverting this because it will require weird patches to make the
dialyzer targets work again.  Also, for better or worse, Yokozuna
relies on riak_kv and ibrwose as dependecnies.  I supppose
rebar.config should reflect that.