title: Using geopy with password authenticated proxy
body: <p>I'm trying to use geopy with a set of coordinates and everything works fine at first.</p>
  
  <pre><code>from geopy.geocoders import GoogleV3
  # some coordinates as example
  latitude, longitude = 24.47646, 85.3095
  geolocator = GoogleV3()
  location = geolocator.geocode('%s, %s' (latitude, longitude))
  address = location.address
  print address
  # this would print something like 
  Unnamed Road, Burhia Ahri, Jharkand 825406, India
  </code></pre>
  
  <p>The enviroment I'm working on requires an authenticated proxy,
  for example purposes let's say something like</p>
  
  <pre><code>proxy_address = 'http://proxy.tests.mydomain'
  proxy_port = 3128
  proxy_user = 'my_user'
  proxy_pass = 'my_pass'
  </code></pre>
  
  <p>Asuming the requirement of authenticated proxy to make it work, I've looked at geopy <a href="https://github.com/geopy/geopy" rel="nofollow noreferrer">github page</a> and <a href="http://geopy.readthedocs.io/en/latest/" rel="nofollow noreferrer">the docs</a> and even if proxies are mentioned, not a single valid url is found.</p>
  
  <p>It seems like sending a dictionary with the 'proxies' parameter is supported, but there is no user/password authenticated variant mentioned anywhere.</p>
  
  <p>Is there any way that something like this is doable?</p>
  
  <pre><code>geolocator = GoogleV3(proxies={'http': proxy_address,
                                 'password': my_user + my_pass})
  </code></pre>
  
  <p>Edit: Spelling </p>