Ahead of the iPhone 5c itself, Apple's iPhone 5c Case ($29) has arrived in our offices. The silicone rubber case is lined with microfiber on the inside, and includes Sleep/Wake and volume button protection. It's quite light, with the empty space left by a 5 x 7 grid of 5/16" holes helping to keep the weight down, while also oddly exposing only portions of the iPhone 5c's rear labeling. We received the black version for review; there are also…