Changes

* Alpha Channel (includes betas)

* Nightly Channel https://aus-staging.mozilla.org:8711/update2/0/%PRODUCT%/%VERSION%/%BUILD_ID%/%BUILD_TARGET%/%LOCALE%/update.xml

A "Channel Manager" extension that offers a UI for managing the channel setting, and preferences such as update frequency etc can be offered to people wishing to join the Beta/Alpha/Nightly channels.