By Bethan John BERLIN (Reuters) - More than 2,000 German mosques have invited Germans of all religions to join their Friday prayers to present a united front against the Islamic State to try to dissuade young Muslims from traveling to fight with radical Islamists in Syria and Iraq. Germany's four main Muslim groups an**unced their plan on Tuesday in response to concerns that German Muslims are joining IS and returning home with radical ideas and combat experience, posing a domestic security threat. ...