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.
There are some rules which only affect migration files, and we cannot
enable them if we're excluding those files from being inspected.
We're also changing migrations related to the Rails/TimeZone rule
slightly because these fields were already changed afterwards, so we
aren't changing the schema.
DEPRECATION WARNING: Directly inheriting from ActiveRecord::Migration
is deprecated. Please specify the Rails release the migration was
written for:
class MigrationClass < ActiveRecord::Migration[4.2]
(called from require at bin/rails:4)
