added wrapper_options argument to def input

Removed this deprecation warning:

    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 render at /home/vagrant/.rvm/gems/ruby-2.0.0-p353@global/bundler/gems/simple_form-d7306558665d/lib/simple_form/wrappers/leaf.rb:15)