fix test

Is this what you really wanted to do?

Also, I have a question: is this really a parallel-each? I mean, the `next` callback is called in order for every array element and since javascript is single threaded, every call will be executed **sequentially** and **in order**. The closest thing to a parallel execution that one could do (it's really just an async execution, anyway) is passing a callback that wraps all its content in a `setTimeout` so that the callbacks will be executed asynchronously (like you've done in the first test) but this is up to the user of the `each-async`, it's not done automatically by the utility. Am I right?