Include the field_id in the context of _as_table_helper
This makes it possible to refer to the field that is being edited by
it's ID (in for example Javascript).
Patch by: "Mario Ferraro" <fadinlight@gmail.com>
A list of bugs is available in the Google App Engine SDK project on Google Code.
The issue tracker is at http://code.google.com/p/googleappengine/issues/.