Add pinning config for stretch

modules/rhizo_base/manifests/apt.pp

@@ -30,6 +30,11 @@ class rhizo_base::apt::common {
       content => 'APT::Get::AllowUnauthenticated "true";',
     }
 
+  file { '/etc/apt/preferences.d/pinning.pref':
+      ensure  => present,
+      source  => "puppet:///modules/rhizo_base/$lsbdistcodename-pinning.pref",
+    }
+
   apt::source { 'rhizomatica':
       location          => 'http://dev.rhizomatica.org/ubuntu/',
       release           => 'precise',