Hello, upgrade. The Nexus 7 was amongst our favorite tablets in 2013, and Android loyalists have been wondering when its successor would ship for some time now. The answer is here, and it's the HTC-built Nexus 9. Straddling the form factor fence between a 7-inch slate and a 10-inch slate, the 8.9-inch Nexus 9 is a new size that just might...