After filing for bankruptcy less than a year ago, Spirit Airlines is going through the same process again after a failed reorganization of the struggling discount airline, the company said Friday.  The airline’s President and CEO, Dave Davis, wrote in an open letter to customers that the Chapter 11 restructuring process would "ensure the long-term success of our company so we can continue to serve our Guests well into the future."Spirit added that "virtually every major airline has used these tools to impro ...