Jordan Cohen is quite possibly the most ebullient person you will ever talk to. His sunny attitude comes through the minute he picks up the phone to talk about his new book. It’s perhaps the key reason he’s become the no. 1 RE/MAX real estate agent in the world and a go-to agent who sells some $300 million in residential real estate a year to top athletes, music stars and actors alike. “His enthusiastic energy could easily light up the…