Fix uninitialized variable lint

Author: justinstoller

manifests/mod/version.pp

@@ -1,4 +1,6 @@
-class apache::mod::version {
+class apache::mod::version(
+  $apache_version = $::apache::apache_version
+) {
 
   if ($::osfamily == 'debian' and versioncmp($apache_version, '2.4') >= 0) {
     warning("${module_name}: module version_module is built-in and can't be loaded")