fixed issue 1331, unkown http_x_forwarded_for, thanks Tyrone

VERSION

@@ -1 +1 @@
-Version 2.4.1-alpha.2+timestamp.2013.02.13.08.40.47
+Version 2.4.1-alpha.2+timestamp.2013.02.13.08.47.47

gluon/main.py

@@ -132,9 +132,8 @@ def get_client(env):
     if all fails, assume '127.0.0.1' or '::1' (running locally)
     """
     g = regex_client.search(env.get('http_x_forwarded_for', ''))
-    if g:
-        client = (g.group() or '').split(',')[0]
-    else:
+    client = (g.group() or '').split(',')[0] if g else None
+    if client in (None, '', 'unkown'):
         g = regex_client.search(env.get('remote_addr', ''))
         if g:
             client = g.group()