Arduino 1.7

#define LED_PIN 13
#define BUTTON_PIN 3
void setup(){
pinMode(LED_PIN, OUTPUT);
pinMode(BUTTON_PIN, INPUT_PULLUP);
}

boolean buttonWasUp = true;
boolean ledEnabled = false;

void loop(){
boolean buttonIsUp = digitalRead(BUTTON_PIN);

if (buttonWasUp && !buttonIsUp) {
delay(10);
buttonIsUp = digitalRead(BUTTON_PIN);
}
if(buttonIsUp && !buttonWasUp){
ledEnabled = !ledEnabled;
digitalWrite(LED_PIN, ledEnabled);
}
buttonWasUp = buttonIsUp;
}