As growth slows for Google Inc., the search giant is pulling an important new sales lever. In a blog post on Thursday, the company said it will let software developers pay to promote their apps in the Play store for the first time. It described the program as a “pilot” involving a limited number of users. The Play store, Google’s version of Apple Inc.’s App Store, is home to more than one million apps, plus games, movies and more for phones running Google’s Android operating system. Google built a $50 billion-plus business around advertisers promoting products and services to users based on their search queries. Until now, it hasn’t allowed app developers and others to promote their wares in the Play store. Instead, it has relied on human curators and algorithms to choose the apps and other content featured on the store’s virtual shelves. Apple doesn’t have ads in its App Store. http://www.marketwatch.com/story/google-opens-up-p...