Pin curator to 3.5.1

elasticsearch-curator 4.0 introduced completely new everything. It will
take some work to support it and all of the new features so pin to 3.5.1
for now. This will keep index deletes working while we add the support.

Change-Id: Iea4e8794d2b953cfdd59ff7907420dffb3de4dff

manifests/curator.pp

@@ -28,7 +28,8 @@ class logstash::curator (
     }
   } else {
     package { 'elasticsearch-curator':
-      ensure   => 'latest',
+      # Pin until we add support for the new stuff in 4.0
+      ensure   => '3.5.1',
       provider => openstack_pip,
     }
   }