Apple's next iPhone is once again rumored to sport a metal back using tech Apple's had a license to since 2010, but has not used much.(Credit: Josh Lowensohn/CNET)After a brief hiatus, the long-standing rumor that Apple will employ more metal in the iPhone, has made a return -- and even taken a new twist.Citing unnamed industry sources, Korean news site ETnews says Apple will use Liquidmetal technology for the next iPhone, which the outlet boldly...