Log executed maxadmin commands on info log level

When maxadmin commands are executed, they are logged at the info
level. This should help when the admin interface is being debugged.

server/modules/routing/cli/cli.c

@@ -271,6 +271,8 @@ execute(MXS_ROUTER *instance, MXS_ROUTER_SESSION *router_session, GWBUF *queue)
         queue = gwbuf_consume(queue, GWBUF_LENGTH(queue));
     }
 
+    MXS_INFO("MaxAdmin: %s", session->cmdbuf);
+
     execute_cmd(session);
     return 1;
 }