(Adds protest in Bahrain, attorney general comment) MANAMA, Dec 30 (Reuters) - Security forces clashed with demonstrators outside the home of the detained head of Bahrain's main Shi'ite Muslim opposition group on Tuesday, a Reuters journalist said. The security forces fired tear gas rounds to disperse the gathering in Bilad al-Qadeem village and some protesters hurled rocks and iron rods at police, he said. Sheikh Ali Salman, head of the al-Wefaq Islamic Society, was arrested on Sunday after leading a protest rally against last month's elections. ...