Although it's already executed when deploying with capistrano, heroku
installations don't use capistrano for deployment, so we're also
executing it when upgrading.
This isn't a one-time task, so it makes sense to have it executed on
every release.
I was thinking of leaving these tasks empty, so in the future we could
use them again if we rename or remove more settings. But since we
haven't renamed nor removed any settings for more than seven months, and
we've only used these tasks once, I'm simply removing the tasks. It's
easy to add them back if we ever need them.
