Fail when we can't work out the langpack version
[fj] Recover from tarball

https://bugzilla.mozilla.org/show_bug.cgi?id=475243
Using:
https://bugzilla.mozilla.org/attachment.cgi?id=358711

XPI was too old to find a matching en-US, so reverted to using the
tarball
[fj] update to latest templates