title: Sequelizejs: findAll and count associations at the same time
body: <p>say I have two models: <code>Post</code> and <code>Comment</code>, now I can use <code>Post.findAll()</code> to get all posts, but I also need the comment count of each post, I can make a loop and use <code>post.countComments()</code> to get the count, but is it possible to do that in one query? thanks</p>