Thanks for this!

Could you include a comment right on top of this line explaining why this initializer is here?
It would be pretty much this pull request description, but it would be great if you also include a link to some place where the problem is better explained. For example:

```ruby
  # Ensure BettertabsHelper is globally available.
  # Otherwise, if config.action_controller.include_all_helpers = false, the Bettertabs helper would not be included.
  # More info about this issue:
  # http://stackoverflow.com/questions/8797690/rails-3-1-better-way-to-expose-an-engines-helper-within-the-client-app
  initializer 'bettertabs.action_controller' do |app|
    # ...
  end
```