Full-text search (search by person name + location)

[gimite]

Switch to search API provided by GAE ( https://developers.google.com/appengine/docs/python/search/ ) instead of hand-made indexing.

The code has been submitted, but currently disabled by a config.

Blocking bugs to launch it: #189 #180 #206

Requirements:

• Allow search by person name + location (city, town, etc.).
  • Currently only by person name.
• Make sure a search query matches at least a part of person name.
  • Otherwise, the feature could allow querying for a neighborhood name and scrape a list of people there, which we agreed is a capability we don't want to provide with ordinary users to protect users' privacy.
• Rank person name match higher than location match.
  • e.g., Query [shibuya] should return people with name "shibuya" first (if available), not people in Shibuya Ward.
• Keep script variant support (e.g., search hiragana by katakana and Latin alphabet) already available.

[gimite]

@prazuma will work on this.