Explicitly Specify riak_core dependencies to update their locations/tags

So various repositories have moved, making riak_core v0.13.0 actually hard to resolve the dependencies for. 

Thankfully rebar is sensible enough that if i specify the right dependencies before riak_core, (along with the correct locations and tags) then it will pull them down first and see that riak_core's deps are met. 

Yeah, I'm pretty sure everything still works, but I need to check distribution, like with the other ticket.