Update server.rb

Author: gjtorikian

hooks/ruby/configuring-your-server/server.rb

@@ -2,6 +2,6 @@
 require 'json'
 
 post '/payload' do
-  push = JSON.parse(params[:payload])
+  push = JSON.parse(request.body.read)
   puts "I got some JSON: #{push.inspect}"
 end