import urllib2
import json

url="http://letsrevolutionizetesting.com/challenge.json"
opener = urllib2.build_opener()
opener.addheaders = [('User-agent', 'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/30.0.1599.101 Safari/537.36')]

def follow(url):
    print url
    page = opener.open(url).read()
    print page
    url = json.loads(page)['follow']
    url = url.replace('challenge?', 'challenge.json?')
    follow(url)

follow(url)