Replace ev and eio calls with uv

So, this pull request replaces the old EIO and EV calls with calls to libuv instead. Those are preferred for 0.8.x and now mandatory for 0.10.x.

Right now the request builds but I still get errors in tests; I probably need to handle passing the results and errno back and forth in a different way, and I'm not sure about the way the uv_ref and uv_unref calls are made.

But I still wanted to get it started to get the discussion going.