ryanb/nested_form — pull request #240 by timsly (2013-02-18 14:31:30+00:00)
Title: Added posibility specify helper for link_to_add and link_to_remove

Sometimes we need specify tag that `link_to_add` or `link_to_remove` generated.
So i have added posibility to specify `:helper` options to choose view helper that generate link

```ruby
= f.link_to_add 'Add new task', :tasks, helper: :button_tag
```