Setting the `JackUp.Processor` path to `/assets.json` made it not include the file in the params. Without the `.json`, it correctly saved the Asset record with the attached file, but then returned a 406 "content not acceptable" error since the controller only responds to JSON, and it was processed as HTML. This way it accepts the HTML request and returns JSON to JackUp.
* Use expect syntax * Use `have_css` instead of assuming `find` will not raise an exception
* Capybara looks in spec/features now * Add selenium-webdriver to Gemfile