remote avatars: support for https-based avatars

Bug #650931

Change-Id: Ib502899193c211f0ab80447734ca90f072e0fe73
Signed-off-by: Francois Marier <francois@catalyst.net.nz>

htdocs/lib/user.php

@@ -1893,6 +1893,9 @@ function remote_avatar($email, $size, $notfound) {
     }
 
     $baseurl = 'http://www.gravatar.com/avatar/';
+    if (stripos(get_config('wwwroot'), 'https://') === 0) {
+        $baseurl = 'https://secure.gravatar.com/avatar/';
+    }
     if (get_config('remoteavatarbaseurl')) {
         $baseurl = get_config('remoteavatarbaseurl');
     }