Ensure latest version of python-jenkins

For JJB and the safe shutdown script we want to ensure the latest
version of python jenkins. This is necessary to pull in new features and
it is what we test against so makes sense to have installed.

Change-Id: I135faa6eef4b2de6303b49f598d6fc9d44031642

manifests/job_builder.pp

@@ -22,7 +22,7 @@ class jenkins::job_builder (
 
   if ! defined(Package['python-jenkins']) {
     package { 'python-jenkins':
-      ensure   => present,
+      ensure   => latest,
       provider => 'pip',
     }
   }

manifests/master.pp

@@ -228,7 +228,7 @@ class jenkins::master(
   # Jenkins management utility scripts
   if ! defined(Package['python-jenkins']) {
     package { 'python-jenkins':
-      ensure   => present,
+      ensure   => latest,
       provider => 'pip',
     }
   }