Add hidden setting to allow foreign post requests

See #55

Signed-off-by: Jesús <heckyel@hyperbola.info>

server.py

@@ -204,7 +204,9 @@ def site_dispatch(env, start_response):
         method = env['REQUEST_METHOD']
         path = env['PATH_INFO']
 
-        if method == "POST" and client_address not in ('127.0.0.1', '::1'):
+        if (method == "POST"
+                and client_address not in ('127.0.0.1', '::1')
+                and not settings.allow_foreign_post_requests):
             yield error_code('403 Forbidden', start_response)
             return