Allow passing extra java opts and proxy env

Change-Id: I4b0350c24ff461a9c08c71ee587dd08570ce2929
diff --git a/docker/swarm/stack/aptly.yml b/docker/swarm/stack/aptly.yml
index 5570c40..36c719b 100644
--- a/docker/swarm/stack/aptly.yml
+++ b/docker/swarm/stack/aptly.yml
@@ -1,3 +1,5 @@
+classes:
+- system.docker
 parameters:
   _param:
     docker_image_aptly:
@@ -9,6 +11,8 @@
         aptly:
           environment:
             EMAIL_ADDRESS: ${_param:admin_email}
+            https_proxy: ${_param:docker_https_proxy}
+            http_proxy: ${_param:docker_http_proxy}
           service:
             api:
               deploy: