Fix demo app

- Remove unnecessary gems
- Fix Sidekiq Web URL

demo/Gemfile

@@ -1,8 +1,6 @@
 source 'https://rubygems.org'
 
 gem 'rails'
-gem 'sinatra'
-gem 'celluloid'
 gem 'launchy'
 gem 'sidekiq', github: 'mperham/sidekiq'
 gem 'sidekiq-limit_fetch', path: '..'

demo/Rakefile

@@ -78,7 +78,7 @@ namespace :demo do
       Rack::Server.start app: Sidekiq::Web, Port: 3000
     end
     sleep 1
-    Launchy.open 'http://127.0.0.1:3000/workers?poll=true'
+    Launchy.open 'http://127.0.0.1:3000/busy?poll=true'
   end
 
   def run_sidekiq_workers(options)