KABUL (Reuters) - Three Americans standing trial in Afghanistan Monday for imprisoning and torturing Afghans were given a week to provide evidence, which they say was withheld by U.S. authorities, proving that they had official clearance. The leader of the group, ex-soldier Jonathan "Jack" Idema, said his group hunted "terrorists," but was disowned by the U.S. government after their arrest because their case followed in the wake of the Abu Ghraib prisoner abuse scandal in Iraq. Wearing khaki fatigues, combat boots and dark glasses, and speaking through an interpreter, the bearded Idema told Judge Abdul Basit Bakhtyari that "political motives"...