Behind-the-scenes, celebrities like Kristin Davis, Kyra Sedgwick and Jennifer Lopez put their covetable locks to the test on a daily basis, what with all the hot lights, long hours, frequent coloring and constant heat styling.So, how do they pull off gorgeous hair that lands them on the red carpet leader board every time? Mitch Stone, an award-winning stylist who has tended to those same tresses, clears up the mystery with his new line of multi-tasking hair formulas, Mitch Stone Essentials ($...