It was a year ago at Computex that Acer unveiled the Aspire S7, a skinny sliver of a thing that turned out to be one of our favorite Ultrabooks of 2012. Now, 12 months later, the company is unveiling the Aspire S7. A much-improved S7, to be precise. Going into the second half of the year, there's only to be a 13-inch version (the 11-incher's been discontinued), and it has much the same industrial design, with a lightweight chassis and Gorilla Glass lid. The differen