Heat waves aside, this last weekend has proven to be a fairly rough one for e-book sellers. In spite of backing off a bit from its initial demands, there have apparently been some major changes afoot in the iOS App Store, with a number of apps scaling back access to their online e-book markets or being pulled from the store altogether. Kobo, one of the former, told The Wall Street Journal (which also reported on its own iOS woes) it was informed on Saturday that it needs to stop selling books through its app. The Google B