Annotate should reset the cached information about columns because Annotate may output old information if we load ActiveRecord::Base class in migration files.

For example, if we have a following migration file and execute 'rake db:migrate', Annote does not output the default value and a not null constraint of the `some_value` column.

```ruby
class CreatePosts < ActiveRecord::Migration
  def change
    create_table :posts do |t|
      t.integer :some_value
    end

    # add a not null constraint to the some_value column

    # should update some_value with not null values
    # because records might exist which have null value in the some_value column

    Post.update_all(some_value: 1)

    change_column_null(:posts, :some_value, false)
    change_column_default(:posts, :some_value, 1)
  end
end
```

This commit fixes the above issue.

Set model_dir to ["app/models"] if not set (fixes #265)

Runs annotate on 'rake db:rollback' too

show foreign keys when run on rake task

ignore default value for jsonb

Quote each value in default arrays

Previously, quoting an array fell back to `inspect`, which is ok for
strings, but not good for BigDecimals, for instance.

Annotate fixtures for nested models

Invoke get options task before annotating migrations

[ fixes #252 ]

This reverts commit 067ce522.

Prefer SQL column type over normalized AR type

fix issue where serializer-related flags weren't being honored

Check if model has skip tag in annotate_model_file

Potentially addresses issue# #167
Annotate_model_file is called automatically on all files in models directory and does not check if model contains SkipSchemaAnnotations tag.

Adds support for foreign key annotations

Test on Ruby 2 versions

Do not add excessive blank lines when source has Windows EOLs

options[:model_dir] seems to be an array now