slim-rails gem crush on start `register_config_processor': wrong number of arguments
<p>when I'm adding <code>slim-rails</code> to <code>Gemfile</code> and starting my app, it crashes with such error:</p>

<pre><code>/Users/rado/.rbenv/versions/2.3.1/gemsets/project/gems/sprockets-4.0.0.beta2/lib/sprockets/processing.rb:211:in `register_config_processor': wrong number of arguments (given 4, expected 2..3) (ArgumentError)
  from /Users/rado/.rbenv/versions/2.3.1/gemsets/project/gems/sprockets-4.0.0.beta2/lib/sprockets/processing.rb:53:in `register_preprocessor'
  from /Users/rado/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/slim-rails-3.1.1/lib/slim-rails/register_engine.rb:33:in `block in _register_engine'
  from /Users/rado/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sprockets-rails-3.1.1/lib/sprockets/railtie.rb:178:in `block in build_environment'
  from /Users/rado/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sprockets-rails-3.1.1/lib/sprockets/railtie.rb:177:in `each'
  from /Users/rado/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sprockets-rails-3.1.1/lib/sprockets/railtie.rb:177:in `build_environment'
</code></pre>

<p>My <code>rails version</code> is <code>5.0.0.1</code>
Anybody knows how to fix this?</p>