Specification of Language Pack UI for Applications and Extensions

Requirements

Applications and extensions should be able to have separate "locale packs" which are downloaded separately to add non-primary language support to the Application or Extension. The application or extension install.rdf and the AMO update service will provide the URIs of available language packs for applications and extensions. The UI should probably hook somehow on to the extension manager so that langpacks are automatically offered to non-English users, and so that additional langpacks are visually tied to the extension.