Added: session hijacking through rack protection
Reminder: escape urls
Fixed: Bot.read_by_screen_name throws better Not_Found error.
Updated: Bot_Code function categories.
Touchups/Additions: Ok, Ok::Validate
Fixed: Escape_All handles embedded arrays, hashes
Fixed: Validate uses :empty? only if object responds to it.
Changed: Ok::Model.create -> returns a newly initialized object
Fixed: Bot_Code :create
Fixed: code is escaped, encoded before DB insert.