by COKIE & STEVE ROBERTS On the popular TV drama "Downton Abbey," the central character, Lord Grantham, turns to his dinner guests and smirks, "There always seems to be something of the Johnny Foreigner about the Catholics."We cherish our heritage as a "nation of immigrants," and yet we resent and reject each wave of newcomers: Catholics and Jews, Italians and Irish, Japanese and Chinese. Since 9/11, Muslims have topped our list of suspicious "Johnny Foreigners." And since the Boston bombers were Muslims of Chechen origin, their vicious attack has spawned a cynical attempt to rekindle nativist anxieties and thwart immigration reform.Sen. Rand Paul of Kentucky offered a particularly egregious example of immigrant-bashing.