Change the value of the ensure parameter to 'installed'; otherwise, r…

…epeated Puppet runs keep changing the value from the version number of the virtualenv package to 'true'.

manifests/init.pp

@@ -217,7 +217,7 @@
 
   if $manage_virtualenv {
     package { $::puppetboard::params::virtualenv:
-      ensure => $manage_virtualenv
+      ensure => installed,
     }
   }