BEIRUT (Reuters) - Syria's rebel al-Nusra Front formally pledged allegiance to al Qaeda leader Ayman al-Zawahri but appeared to distance itself from a recently announced merger with al Qaeda's Iraq branch under the banner Islamic State of Iraq and Levant. According to an audio tape posted online on Wednesday, Abu Mohammad al-Golani, leader of the Syrian group, said: "The sons of Nusra Front renew their pledge (of allegiance) to the Sheikh of Jihad Ayman al-Zawahri and declare obedience. ...