puppet: Rename zulip_internal to zulip_ops.

The old "zulip_internal" name was from back when Zulip, Inc. had two
distributions of Zulip, the enterprise distribution in puppet/zulip/
and the "internal" SAAS distribution in puppet/zulip_internal.  I
think the name is a bit confusing in the new fully open-source Zulip
work, so we're replacing it with "zulip_ops".  I don't think the new
name is perfect, but it's better.

In the following commits, we'll delete a bunch of pieces of Zulip,
Inc.'s infrastructure that don't exist anymore and thus are no longer
useful (e.g. the old Trac configuration), with the goal of cleaning
the repository of as much unnecessary content as possible.

puppet/zulip_internal/files/cron.d/graphite_backup

@@ -1,4 +0,0 @@
-MAILTO=root
-SHELL=/bin/bash
-
-0 3 * * * zulip /home/zulip/zulip/puppet/zulip_internal/files/graphite/daily_rsync_backup.sh

puppet/zulip_internal/manifests/init.pp

@@ -1,2 +0,0 @@
-class zulip_internal {
-}

puppet/zulip_internal/manifests/redis.pp

@@ -1,7 +0,0 @@
-class zulip_internal::redis inherits zulip::redis {
-  include zulip_internal::base
-
-  File[ "/etc/redis/redis.conf"] {
-    source => "puppet:///modules/zulip_internal/redis/redis.conf",
-  }
-}

puppet/zulip_ops/files/cron.d/graphite_backup

@@ -0,0 +1,4 @@
+MAILTO=root
+SHELL=/bin/bash
+
+0 3 * * * zulip /home/zulip/zulip/puppet/zulip_ops/files/graphite/daily_rsync_backup.sh