Check out how people make DIY cnc routers, etc. Attach a motor to a threaded rod, then attach a nut to the handle. As the motor turns one way, the nut will push open the handle, as the motor turns the other, it will pull it closed. The motor will need to pivot some, which just means more 3d printing 
. You don't really need a "servo" that's overkill, you need 2 limit switches, because all you need to know is when your handle is all the way open and all the way closed.
Check out this page if you still want to think about a servo - there's not much to a servo but a dc motor, an h-bridge motor driver, a potentiometer, and some gears. The only thing that's all that smart is a servo is taking the PWM signal and converting that into angular degrees. With the Photon, you can just read the pot value directly and turn off power to the motor when you are near that value. Servos use PID algorithms to slow the speed of rotation as they near their setpoint, but that also seems like overkill.