Allow aptly to run cron jobs

Change-Id: I480190b1ec0a1ad9c0f6187eb510c9e7e18af5ae
diff --git a/aptly/server/single.yml b/aptly/server/single.yml
index 9f2d401..55e4b9c 100644
--- a/aptly/server/single.yml
+++ b/aptly/server/single.yml
@@ -8,6 +8,12 @@
     aptly_server_secure: true
     aptly_server_mirror_sources: false
     aptly_server_mirror_ubuntu_sources: ${_param:aptly_server_mirror_sources}
+  linux:
+    system:
+      cron:
+        user:
+          aptly:
+            enabled: true
   nginx:
     server:
       site: