Arduino servo acts weird with photocell (lightsensor)
Servos accept a signal from 0 to 180, with 90 being the center point on the servo. analogRead() will output a number from 0 to 1023. The arduino "map" function makes a conversion easy to do. just replace

int newAngle = reading / 2;


with

int newAngle = map(reading, 0, 1023, 0, 180);


you can read more about the map function here: http://arduino.cc/en/reference/map

It is hard to tell from the picture that everything else is wired correctly, but this should fix up your code.