Google is knocking at your front door. It wants to come inside and quietly take control of everything in your home and your digital life. According to CNN, for years, Google has been buying and building the tools to do just that. This week's $3.2 billion purchase of Nest, a smart thermostat and smoke detector company, is just the latest step. Google already dabbles in email, smartphones, self-driving cars, social networking, smart glasses, television, robots and now connected devices.