Nginx: Do not use separate location for /images/ URI shortcut to avoid conflicts with custom config includes.

Revert partially 449a5abe to restore backward compatibility with IP based vhosts.

Issue #2116395 by realityloop - Nginx: Extend protection for config files and use 404 instead of 403.

Nginx: Replace inappropriate, legacy keyword gulag with neutral and technically correct limreq everywhere.

The cache_form bin is excluded in drupal_flush_all_caches() but if not purged, it may break tasks with mysterious errors thanks to garbage collected.

Nginx: Separate support for static and dynamic .json requests/URIs to avoid breaking Services for GET requests.

This assumes that static .json files with fast 404 are expected only in the sites/foo.com/files tree. Everything else is expected to be dynamic and sent to Drupal via Speed Booster caching layer only.

See http://trac.nginx.org/nginx/ticket/306 for context and more details.

Nginx: Add support for domain specific /robots.txt mapped to static files/$host.robots.txt to make it possible to manage it per domain also when Domain Access module is used.