Michael M. Santiago/Getty Images Big-money investors are the most bullish they've been in years, according to a new Bank of America survey. All sorts of indicators are at multiyear extremes as stocks hover near record highs. BofA says traders are getting so overzealous that it's close to triggering a sell signal. It's December and there's something in the air. No, it's not the sweet smell of Christmas cookies and hot cocoa (although that sounds great). It's a wave of unabashed bullishness that's ...