bundles/cron: provide some environment, also manage /etc/crontab

bundles/cron/items.py

@@ -1,4 +1,11 @@
-files = {}
+files = {
+    '/etc/crontab': {
+        'content_type': 'mako',
+        'context': {
+            'min': (node.magic_number%60),
+        },
+    },
+}
 
 directories = {
     '/etc/cron.d': {
@@ -11,5 +18,9 @@ directories = {
 
 for crontab, content in node.metadata.get('cron', {}).items():
     files['/etc/cron.d/{}'.format(crontab)] = {
-        'content': content + "\n",
+        'source': 'cron_template',
+        'content_type': 'mako',
+        'context': {
+            'cron': content,
+        }
     }