database: Redesign search functions with GAE Search API.

This change includes the new indexing functions using GAE Search API
inside indexae.go. A flag in the main package gae_search is used to
control whether to use the new search functions.

The final goal is to replace index.go with the new methods and deprecate
the current stemming algorithm and use the one from Search API.
Functions to replace original ones are implemented and labeled "2" in
their names.

Local development is unaffected with gae_search flag turned off. Local
deployment with GAE Search API needs to use dev_appserver and an
app.yaml file, which is included. The instruction on how to do so will
be added to the wiki page when the code is submitted.

Change-Id: Ia889684176bafb2d6eac075061c06a733667c914
Reviewed-on: https://go-review.googlesource.com/23794
Reviewed-by: Alan Donovan <adonovan@google.com>
Reviewed-by: Andrew Gerrand <adg@golang.org>
7 files changed