Move queryinfo to future

I went back and forth on this when I originally did it and after
starting to write docs and play with the API i decided I went the
wrong way.

This moves the "Query Info" into the `RiakFuture` itself. By doing so
it eliminates the need to duplicate the query info in both the
responses and the `FailureInfo` class I'd created. 

Now the core operations simply override `getQueryInfo()` and return it rather than
having to include it in their respective responses. The new
netty-like `RiakFuture` plays fine with operations that don't
return anything since you can simply check `isSuccess()` after
calling `await()`.

Example:

```Java
RiakFuture<Void, Location> future = client.executeAsync(deleteValueCommand);
future.await();
if (future.isSuccess())
{
    System.out.println("Successfully deleted " + future.getQueryInfo().getKey());
}
```