Pass emitted arguments to client

Make the emitted arguments available to the `ewait.waitForAll` and `ewait.waitForAny` callbacks. Only the arguments from the last emitter to emit will be available in the case of `ewait.waitForAll`.

Thanks for taking the time to look at my first pull request. I agree it makes sense to pass the emitted arguments as an array to the client in the case of ewait.waitForAll. Returning an array in which each entry contains the arguments returned by the corresponding event emitter would require some surgery to multiple.js. There is currently no way to determine which subject emitted the event hence the arguments position in the array would be arbitrary. Is this something you could help with?