Merge filter and notification servers, have both tasks run on the same servers

manifests/filterserver.pp

-node 'server5', 'server6', 'server7', 'server11', 'server12', 'server15', 'server19', 'filter1', 'filter2', 'filter3', 'filter4', 'filter5', 'filter6' {
-  include base, filterserver
+node 'server5', 'server6', 'server7', 'server11', 'server12', 'server15', 'server19', 'filter1', 'filter2', 'filter3', 'filter4', 'filter5', 'filter6', 'notification1', 'notification2' {

[Felix Dahlke, 2014/01/30 13:51:48]

How about taking notification1 and 2 out of here and repurposing them as filter7
and filter8 later? (Can be done in a follow-up of course.)

+  include base
 
+  class {'filterserver':
+    is_default => true

[Felix Dahlke, 2014/01/30 13:51:48]

Not really a fan of this, I'd rather just merge notificationserver into
filterserver if we can't get the two modules to get along. I have some ideas for
achieving that below though.

+  }
+
+  class {'notificationserver':
+    is_default => false
+  }
+
   class {'nagios::client':
     server_address => 'monitoring.adblockplus.org'
   }
 
   class {'statsclient': }
 }