ensure file exists

Signed-off-by: Steven Armstrong <steven@icarus.ethz.ch>

cdist/conf/type/__timezone/manifest

@@ -41,10 +41,14 @@ case "$os" in
     centos)
         __package tzdata --state present
         export require="__package/tzdata"
-        __key_value ZONE \
-            --file /etc/sysconfig/clock \
-            --delimiter '=' \
-            --value "\"$timezone\""
+        __file /etc/sysconfig/clock \
+            --owner root --group root --mode 644 \
+            --state exists
+        require="__file/etc/sysconfig/clock" \
+            ___key_value ZONE \
+                --file /etc/sysconfig/clock \
+                --delimiter '=' \
+                --value "\"$timezone\""
     ;;
     *)
         echo "Your operating system ($os) is currently not supported by this type (${__type##*/})." >&2