Use httpd::vhost $content parameter

Use the new $content parameter of httpd::vhost instead of $template.
This way, the template gets rendered within the scope where it assumes
its variables are, and doesn't need to use the scope object which
doesn't work within a defined type. This will ensure the template keeps
working on puppet 4.

Depends-On: https://review.openstack.org/570824
Change-Id: I8458c930e48c4c0b60e9b4cadd528a2dc899bb7d

manifests/site.pp

@@ -95,7 +95,7 @@ define cgit::site(
     serveraliases => $serveraliases,
     docroot       => 'MEANINGLESS ARGUMENT',
     priority      => $cgit_vhost_priority,
-    template      => 'cgit/git.vhost.erb',
+    content       => template('cgit/git.vhost.erb'),
     ssl           => true,
     require       => [
       File[$staticfiles],