do not raise an error if user config file is corrupted

lib/simple_config.py

@@ -154,7 +154,8 @@ a SimpleConfig instance then reads the wallet file.
             try:
                 d = ast.literal_eval( data )  #parse raw data from reading wallet file
             except Exception:
-                raise IOError("Cannot read config file.")
+                print_msg("Error: Cannot read config file.")
+                return
 
             self.user_config = d