puppet: Move Zulip apt repository to its own manifest.

puppet/zulip/manifests/apt_repository.pp

@@ -0,0 +1,12 @@
+# This only works if zulip::base is included
+class zulip::apt_repository {
+  apt::source {'zulip':
+    location    => 'http://ppa.launchpad.net/tabbott/zulip/ubuntu',
+    release     => 'trusty',
+    repos       => 'main',
+    key         => '84C2BE60E50E336456E4749CE84240474E26AE47',
+    key_source  => 'https://zulip.com/dist/keys/zulip.asc',
+    pin         => '995',
+    include_src => true,
+  }
+}

puppet/zulip/manifests/voyager.pp

@@ -1,19 +1,10 @@
 class zulip::voyager {
+  include zulip::apt_repository
   include zulip::base
   include zulip::app_frontend
   include zulip::postgres_appdb_tuned
   include zulip::redis
 
-  apt::source {'zulip':
-    location    => 'http://ppa.launchpad.net/tabbott/zulip/ubuntu',
-    release     => 'trusty',
-    repos       => 'main',
-    key         => '84C2BE60E50E336456E4749CE84240474E26AE47',
-    key_source  => 'https://zulip.com/dist/keys/zulip.asc',
-    pin         => '995',
-    include_src => true,
-  }
-
   file { "/etc/nginx/sites-available/zulip-enterprise":
     require => Package["nginx-full"],
     ensure => file,