VERSION 1.1 
apt-get with the following command :
       
   1.  sudo apt-get install update
   2.  sudo apt-get install python-dev
   3.  sudo apt-get install python3-dev 
   4.  sudo apt-get install gcc 
   5.  sudo apt-get install python-pip

Next you need to get RPi.GPIO:

   6.  wget https://pypi.python.org/packages/source/R/RPi.GPIO/RPi.GPIO-0.5.11.tar.gz

Uncompress the packages:

   7.  sudo tar -zxvf RPi.GPIO-0.5.11.tar.gz

move into the newly created directory:

   8.  cd RPi.GPIO-0.5.11

install the module by doing:

   9.  sudo python setup.py install
   10.  sudo python3 setup.py install

creating a directory to hold your scripts:

   11.  mkdir /home/pi/scripts

call our script shutdown.py (it is written in python). Create and edit the script by doing:

   12.  sudo nano /home/pi/scripts/shutdown.py

The content of the script: Paste it in the blank area

#!/usr/bin/python
import RPi.GPIO as GPIO
import time
import subprocess

# we will use the pin numbering to match the pins on the Pi, instead of the 
# GPIO pin outs (makes it easier to keep track of things)

GPIO.setmode(GPIO.BOARD)  

# use the same pin that is used for the reset button (one button to rule them all!)
GPIO.setup(5, GPIO.IN, pull_up_down = GPIO.PUD_UP)  

oldButtonState1 = True

while True:
    #grab the current button state
    buttonState1 = GPIO.input(5)

    # check to see if button has been pushed
    if buttonState1 != oldButtonState1 and buttonState1 == False:
      subprocess.call("shutdown -h now", shell=True, 
        stdout=subprocess.PIPE, stderr=subprocess.PIPE)
      oldButtonState1 = buttonState1

    time.sleep(.1)


Press CRTL X  Then Y      
	
Restart the pi
	
	13.  sudo reboot
		
configure our script to run at startup,

   14.  sudo nano /etc/rc.local
   
Add the following to the file 
   
   sudo python /home/pi/scripts/shutdown.py &

Press CRTL X  Then Y  


NOTE:
This procedure needs to be updated for the RPi4. Be sure that RPI.GPIO v .7 and not .5 is installed otherwise Error 'RuntimeError: This module can only be run on a Raspberry Pi!' will occur. 

I renamed the directory and .egg file in '/usr/local/lib/python3.7/dist-packages'  then reinstalled with 'sudo pip3 install RPi.GPIO'. This updated it from '0.5.11' to '0.7.0' and the script worked properly. 

If you decide to make the change to 3.7, be sure to alter the command to the 'rc.local' file from 'sudo python /home/pi/scripts/shutdown.py &' to 'sudo python3 /home/pi/scripts/shutdown.py &' otherwise it won't run at startup.

BTW: I would assume you could do the same for python2 in '/usr/local/lib/python2.7/dist-packages' as well, at which point you wouldn't need to alter the command in 'rc.local'. - Hope it helps.