By SAMANTHA BOMKAMP NEW YORK — Welcome to the 21st century, passengers.Self-serve ticket kiosks and other electronic screens and gadgets aren’t exactly new at airports around the world, but some travelers are hesitant — maybe a little scared — about using them. They prefer the old-fashioned comfort of face-to-face contact with an agent, even if waiting in line slows them down.But there are a growing number of ways to cut time and hassle at the airport, from new kiosks to boarding passes scanned directly from your cellphone screen.