title: Python error: argument -c/--conf is required
body: <p><br>I'm new in python, my native language is C. I'm doing a code in python for a surveillance system triggered by motion using OpenCV. I based my code in the one made by Adrian Rosebrock in his blog <a href="http://www.pyimagesearch.com/2015/06/01/home-surveillance-and-motion-detection-with-the-raspberry-pi-python-and-opencv/" rel="nofollow"> pyimagesearch.com</a>. Originally the code was developed for a Raspiberry Pi with a Pi Camera module attached to it, now I'm trying to adapt to my notebook's webcam. He made a easier tutorial about a simple code for motion detection and it worked very nicely in my PC. But I'm having a hardtime with this other code. Probably it's  a silly mistake, but as begginer I couldn't found a specific answer to this issue.</p>
  
  <p><br>This image have the part of the code that is causing the error (line 15) and  the structure of the project on the left side of the screen. <br><a href="http://i.stack.imgur.com/fWwBZ.png" rel="nofollow">Image of python project for surveillance</a>.</p>
  
  <p><br>Similar part, originall code:  </p>
  
  <pre><code># import the necessary packages
  from pyimagesearch.tempimage import TempImage
  from dropbox.client import DropboxOAuth2FlowNoRedirect
  from dropbox.client import DropboxClient
  from picamera.array import PiRGBArray
  from picamera import PiCamera
  import argparse
  import warnings
  import datetime
  import imutils
  import json
  import time
  import cv2
  
  # construct the argument parser and parse the arguments
  ap = argparse.ArgumentParser()
  ap.add_argument("-c", "--conf", required=True,
      help="path to the JSON configuration file")
  args = vars(ap.parse_args())
  
  # filter warnings, load the configuration and initialize the Dropbox
  # client
  warnings.filterwarnings("ignore")
  conf = json.load(open(args["conf"]))
  client = None
  </code></pre>
  
  <p><br>Until now I only change these things:<br/></p>
  
  <ul>
  <li>Exclude the imports relatives to pi camera.</li>
  <li>Change <code>camera = PiCamera()</code> by <code>camera = cv2.VideoCapture(0)</code>. This way I use notebook's webcam.</li>
  <li><p>Exclude:</p>
  
  <pre><code>camera.resolution = tuple(conf["resolution"])
  camera.framerate = conf["fps"]
  rawCapture = PiRGBArray(camera, size=tuple(conf["resolution"]))
  </code></pre></li>
  <li>Substitute the line <code>for f in camera.capture_continuous(rawCapture, format="bgr", use_video_port=True):</code> by <code>while True:</code>.</li>
  <li>Exclude two lines in program that was <code>rawCapture.truncate(0)</code>.</li>
  </ul>
  
  <p><br>Probably there is more things to repair, if you now please tell me, but first I'd like to understand how solve that mensage error. I use PyCharm in Windows 7 with Python 2.7 and OpenCV 3.1. Sorry for not post the entire code, but once that this is my first question in the site and I have 0 reputation, apparently I can just post 2 links. The entire originall code is in the pyimagesearch.com. Thank you for your time!</p>