TODO:

Intercept calls to:
  - ActiveRecord::ConnectionAdapters::SchemaStatements#add_column
  - ActiveRecord::ConnectionAdapters::TableDefinition#integer
  - ActiveRecord::ConnectionAdapters::Table#integer

From e.g.

class MyMigration < ActiveRecord::Migration
  def change
    create_table :foo do |t|
      t.integer :my_foreign_key # should have used references, but we'll help you
                                # TableDefinition.integer
    end

    change_table :bar do |t|
      t.integer :my_new_foreign_key # Table.integer
    end

    add_column :baz, :my_other_new_foreign_key # SchemaStatements.add_column
  end
end

For each intercepted call
- if not integer, just run default
- if integer and we think it's a foreign key, and no limit specified, default
  limit to 8
- if integer but with specified limit, just run default