Aisle/Features/Language packs

Language packs are great ways to create testable deliverables, with minor install hurdles.

Goals
Paradigms
Use Cases	Aisle/Use Cases/Sprint, Aisle/Use Cases/New localization
Requirements
Phase
Milestone

Language packs should be

• compatible with the build the tester is using.
  • This needs extra work in the addons manager for nightly and aurora
• updating when there's new localization work or an incompatible build
• restartless
• working for more testers than just one

This requires a bit of server-side infrastructure to run a langpack build against the repo and revision that maps to the build a tester is using.

I expect the add-on ID to be bound to the repo the contributor is working on.