apache: Added support for forward proxy with optional caching

apache/templates/proxy.conf.erb

@@ -1,12 +1,21 @@
-<% if @apache_proxy_allow -%>
-ProxyRequests On
-ProxyVia On
+Listen <%= @port %>
+
+<VirtualHost _default_:<%= @port %>>
+  ProxyRequests On
+  ProxyVia On
+
+<% if @cache == true -%>
+  <IfModule mod_disk_cache.c>
+    CacheEnable disk /
+    CacheRoot <%= @cachepath %>
+  </IfModule>
 
-<Proxy *>
-  Order deny,allow
-  Deny from all
-  Allow from <%= @apache_proxy_allow %>
-</Proxy>
-<% else -%>
-ProxyRequests Off
 <% end -%>
+  <Proxy *>
+    Order deny,allow
+    Deny from all
+<% @allow.each do |addr| -%>
+    Allow from <%= addr %>
+<% end -%>
+  </Proxy>
+</VirtualHost>