Add simple support for config/userdb files.

config.py

 parameters_description = { "address": ("string", "0.0.0.0"),
-                           "port": ("int", 12345) }
+                           "port": ("int", 12345),
+                           "userdb": ("string", "") }
 
 class ConfigError:
     pass
@@ -34,6 +35,9 @@ def load_config_from_content(content):
         config.add_param(elts[0].strip(), elts[1].strip())
     return config
 
+def load_config_from_file(filename):
+    f = open(filename)
+    return load_config_from_content(f.read())
 
 
 class UserDB:
@@ -58,3 +62,6 @@ def load_userdb_from_content(content):
         login, password, admin = line.split(2)
         userdb.add_user(login, password, admin)
 
+def load_userdb_from_file(filename):
+    f = open(filename)
+    return load_userdb_from_content(f.read())