ntpd: Use chrony instead of isc-ntpd on CentOS 7.

ntpd/manifests/init.pp

@@ -40,6 +40,13 @@ class ntpd {
         "openbsd": {
             include ntpd::openntpd
         }
+        "centos","redhat": {
+            if versioncmp($::operatingsystemrelease, "7") < 0 {
+                include ntpd::isc-ntpd
+            } else {
+                include ntpd::chrony
+            }
+        }
         default: {
             include ntpd::isc-ntpd
         }