Install gunicorn into the django virtualenv.

I would normally avoid duplicating what the gunicorn cookbook does, but this is literally 4 lines of code; any other solution would be much more intrusive for very little gain.

providers/gunicorn.rb

@@ -22,9 +22,11 @@
 
 action :before_compile do
 
-  include_recipe "gunicorn"
   include_recipe "supervisor"
 
+  django_resource = new_resource.application.sub_resources.select{|res| res.type == :django}.first
+  gunicorn_install :virtualenv => django_resource.nil? ? nil : django_resource.virtualenv
+
   if !new_resource.restart_command
     new_resource.restart_command do
       run_context.resource_collection.find(:supervisor_service => new_resource.application.name).run_action(:restart)