The guitar was laid out at George Dennehy's feet on a black cloth to keep it from moving. Barefoot, he used his right foot to lift the capo. With the left, he held a pick between his toes.Dennehy was born without arms, and he says he is the only known person in the world who plays classical string music using his feet.But he was in Bethlehem on Tuesday for Musikfest showing another side: playing acoustic rock songs as the opening act for the Goo Goo Dolls at the Sands Steel Stage.Before the concert, he put on a short show for a small mob of reporters and photographers.“Sorry it’s taking me a w