Replace ActiveSupport::OrderedHash with Hash because Ruby 1.9 Hash is ordering-aware and we no longer support Ruby 1.8
Bump multi_json to latest version
Fix unsafe constantize calls in admin controllers
Ensure json gem version is at least 1.5.5 [Thanks to Steve Root for
notifying us of this]
Ensure state dropdown reappears during country selection, as required. Fixes #2605
refactor taxonomy tree to use a function

Fixes #2622