Fix broken specs

Some merge after the rails engine, accidently anyone removed the following line on form_helper.rb:

```ruby
input_options['type'] = type
````

without this the input is generated with `type="text"` over `type="filepicker"`, as the [documentation suggest](https://developers.inkfilepicker.com/docs/web/#widgets).

I fixed this. I suggest only accept pull request with specs from now on. I I`ll make a PR to add travis, this way we know we have a broken spec directly on github =)