Use remote_api for shell access on developer.android.com.

This allows Python shell access on developer.android.com
using the remote_api_shell.py script that's bundled with
the App Engine SDK.

Change-Id: If3c979ccbf885905a9cc3840645dcb6a5a50cfa8

scripts/app_engine_server/app.yaml

@@ -4,6 +4,10 @@ runtime: python
 api_version: 1
 
 handlers:
+- url: /remote_api
+  script: $PYTHON_LIB/google/appengine/ext/remote_api/handler.py
+  login: admin
+
 - url: /gae_shell/static
   static_dir: gae_shell/static
   expiration: 1d