Note we're excluding a few files:
* Configuration files that weren't generated by us
* Migration files that weren't generated by us
* The Gemfile, since it includes an important comment that must be on
the same line as the gem declaration
* The Budget::Stats class, since the heading statistics are a mess and
having shorter lines would require a lot of refactoring
We were using the `timestamps` method most of the time, but sometimes we
were creating the columns manually.
Note editing past migrations if fine as long as the SQL they generate
remains identical, which is the case here.
