Fix jenkins::slave::ssh_key scope.

In jenkins::slave the ssh_key variable was scoped to ::ssh_key which is
not valid. It needs to be looked up at local scope.

Change-Id: I5de91e5bcc21b0b682e1e6c34f8f7c1d806b3296
Reviewed-on: https://review.openstack.org/15047
Reviewed-by: Paul Belanger <paul.belanger@polybeacon.com>
Reviewed-by: Monty Taylor <mordred@inaugust.com>
Approved: James E. Blair <corvus@inaugust.com>
Reviewed-by: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins

modules/jenkins/manifests/slave.pp

@@ -12,8 +12,8 @@ class jenkins::slave(
   if ($user == true) {
     class { 'jenkins::jenkinsuser':
       ensure  => present,
-      sudo    => $::sudo,
-      ssh_key => $::ssh_key,
+      sudo    => $sudo,
+      ssh_key => $ssh_key,
     }
   }