This week's free single, "Cool Kids", is about as uncool as the kids from your high school. I am becoming seriously jaded toward iTunes' selection of indie-pop these days. Often they find real diamonds in the rough to promote as free singles. The work of Echosmith is not amongst them. Echosmith is a four person sibling act - three brothers and their vocalist sister put together a little family band out in LA. They are a very, very young group. The eldest brother, Jamie, is just 20 years old…