Alanis Morissette is the mother to a 21 month old son and she doesn’t think that being a parent means you have to stop rockin’. So she has started ROCCK and aired a PSA for it during Jimmy Kimmel Live! Hopefully her ex Ryan Reynolds will be taking that course soon because he is going to need to know how to Rock being a stay-at-home single dad. Not that Blake Lively is pregnant or that they will likely split up. I am not saying that…