cache_valid_time to apt module calls
diff --git a/roles/head-prep/tasks/main.yml b/roles/head-prep/tasks/main.yml
index 37c4b0b..5a51ebf 100644
--- a/roles/head-prep/tasks/main.yml
+++ b/roles/head-prep/tasks/main.yml
@@ -4,6 +4,8 @@
 - name:  Install prerequisites for using PPA repos
   apt:
     name={{ item }}
+    update_cache=yes
+    cache_valid_time=3600
   with_items:
     - python-pycurl
     - software-properties-common