Code review comment for lp:~al-maisan/launchpad/unembargo-email-316488

Hello there!

When security fix packages are un-embargo'ed they are copied to the primary
archive. Since they become publicly available now an announcement email needs
to be sent out.

Pre-implementation call with Celso.

Tests to run:

    bin/test -vv -t package -t upload

P.S.: I retracted this branch from review an hour ago in order to fix 2 test failures I did not notice in time. Now everything is fixed and all the tests pass :)