title: HttpURLConnection ifModifiedSince generates UTC time instead of GMT
body: <p>I have the following method:</p>
  
  <pre><code>public void GetBackground(final int width, final int height, final Long ifModifiedSince,
          final GetBackgroundListener listener)
  {
      new Thread(new Runnable()
      {
          public void run()
          {
              try {
                  String urlString = serviceUri + "/DownloadBackground?width=" + width
                          + "&amp;height=" + height;
                  URL url = new URL(urlString);
                  HttpURLConnection connection = (HttpURLConnection)url.openConnection();
                  if (ifModifiedSince != null) {
                      Log.d(TAG, "Background last modified: " + ifModifiedSince);
                      connection.setIfModifiedSince(ifModifiedSince);
                  }
                  InputStream stream = (InputStream)connection.getContent();
                  if (connection.getResponseCode() == HttpURLConnection.HTTP_NOT_MODIFIED) {
                      listener.onNotModified();
                      Log.d(TAG, "Background not modified");
                  } else {
                      Bitmap background = BitmapFactory.decodeStream(stream);
                      listener.onSuccess(background, connection.getLastModified());
                      Log.d(TAG, "New background");
                  }
              } catch (Exception e) {
                  listener.onError(e);
              }
          }
      }).start();
  }
  </code></pre>
  
  <p>On Android 2.2 it generates the following package:</p>
  
  <pre><code>GET /QurrentService.svc/DownloadBackground?width=480&amp;height=480 HTTP/1.1
  if-modified-since: Thu, 13 Dec 2012 09:11:23 GMT
  User-Agent: Dalvik/1.2.0 (Linux; U; Android 2.2; sdk Build/FRF91)
  Host: qurrentfeed1.1.aliencms.nl
  Connection: Keep-Alive
  </code></pre>
  
  <p>And on Android 4.1:</p>
  
  <pre><code>GET /QurrentService.svc/DownloadBackground?width=800&amp;height=800 HTTP/1.1
  User-Agent: Dalvik/1.6.0 (Linux; U; Android 4.1.2; sdk Build/MASTER)
  Host: qurrentfeed1.1.aliencms.nl
  Connection: Keep-Alive
  Accept-Encoding: gzip
  If-Modified-Since: Thu, 13 Dec 2012 09:11:23 UTC
  </code></pre>
  
  <p>I'm not sure whether it's allowed to send the If-modified-since date as a UTC time, but the server fails to parse the date.
  Is there a way to force the HttpURLConnection to generate a GMT format? Or should I set the header manually like this?</p>
  
  <pre><code>String ifModifiedSinceString = DateUtils.formatDate(new Date(ifModifiedSince), "EEE, d MMM yyyy HH:mm:ss 'GMT'");
  connection.addRequestProperty("If-Modified-Since", ifModifiedSinceString);
  </code></pre>