Rework subscription on webapp.

ConfigHandler is more optional now.
Connection is treated as a service to be injected.

Change-Id: I7efea116fe7ebb895ffdc42aedfe0f1f7b05e874
diff --git a/y2020/www/main.ts b/y2020/www/main.ts
index e4c0f10..46a0e8a 100644
--- a/y2020/www/main.ts
+++ b/y2020/www/main.ts
@@ -1,10 +1,12 @@
 import {Connection} from 'aos/network/www/proxy';
 
 import {ImageHandler} from './image_handler';
-import {FieldHandler} from './field_handler';
+import {ConfigHandler} from 'aos/network/www/config_handler';
 
 const conn = new Connection();
 
+const configPrinter = new ConfigHandler(conn);
+
 conn.connect();
 
 const iHandler = new ImageHandler();