Include mod_wsgi for graphite

If mod_wsgi is not installed, the puppet-graphite module will fail to
start apache because of the WSGI commands in the vhost template. This
patch adds the httpd::mod::wsgi class to take care of it. There is
nothing else in the graphite.openstack.org site.pp node that installs
mod_wsgi so the package resource in the class should not conflict with
anything.

Change-Id: Iaba16663c99a9a3aa6b69ac9b5af6dba22cd3fd2

manifests/init.pp

@@ -31,6 +31,8 @@ class graphite(
   include ::httpd
   include pip
 
+  include ::httpd::mod::wsgi
+
   package { $packages:
     ensure => present,
   }