title: How to integrate payumoney payment gateway with rails 4
body: <p>Included "gem 'active_merchant_payu_in'" in Gemfile. Getting this error while bundle install</p>
  
  <pre><code>/home/waheguru/.rvm/gems/ruby-2.2.0/gems/active_merchant_payu_in-0.0.1/lib/active_merchant_payu_in.rb:2:in `require': cannot load such file -- active_merchant/billing/integrations (LoadError)
  </code></pre>