WYSIWI Editor is causing a deprecation warning in tests

[kenmazaika]

# Running tests:

......................DEPRECATION WARNING: input method now accepts a `wrapper_options` argument. The method definition without the argument is deprecated and will be removed in the next Simple Form version. Change your code from:

    def input

to

    def input(wrapper_options)

See https://github.com/plataformatec/simple_form/pull/997 for more information.
 (called from block in _app_views_posts_index_html_haml___647320704__579095908 at /vagrant/src/defcon/app/views/posts/index.html.haml:20)
........................

Finished tests in 8.753835s, 5.2548 tests/s, 10.5097 assertions/s.

This PR explains how to fix the simple form deprecation warnings in custom simpleform inputs.

heartcombo/simple_form#997