Use instance variables in puppet template

Using local ruby variables in puppet ERB templates was deprecated in
puppet 3 and doesn't work any more in puppet 4. Access these values as
ruby instance variables instead.

Change-Id: I06bdd6f5b1f13c4970c5e3e9dc8be4cf8d919b03

templates/dual-elasticsearch.vhost.erb

@@ -2,9 +2,9 @@
   ServerName <%= @vhost_name %>
   ServerAdmin <%= @serveradmin %>
 <% if @serveraliases.is_a? Array %>
-<% serveraliases.each do |name| %><%= "  ServerAlias #{name}\n" %><% end %>
+<% @serveraliases.each do |name| %><%= "  ServerAlias #{name}\n" %><% end %>
 <% elsif @serveraliases != '' %>
-<%= "  ServerAlias #{serveraliases}" %>
+<%= "  ServerAlias #{@serveraliases}" %>
 <% end %>
 
   ErrorLog ${APACHE_LOG_DIR}/<%= @vhost_name %>-error.log
@@ -32,8 +32,8 @@
     ProxyPassReverse <%= @elasticsearch_prefix %> <%= @elasticsearch_url %>/
   </IfModule>
 
-  DocumentRoot <%= docroot %>
-  <Directory <%= docroot %>>
+  DocumentRoot <%= @docroot %>
+  <Directory <%= @docroot %>>
     Options -Multiviews
     <IfVersion >= 2.4>
     Require all granted