install: Remove references to "Zulip Voyager".

"Zulip Voyager" was a name invented during the Hack Week to open
source Zulip for what a single-system Zulip server might be called, as
a Star Trek pun on the code it was based on, "Zulip Enterprise".

At the time, we just needed a name quickly, but it was never a good
name, just a placeholder.  This removes that placeholder name from
much of the codebase.  A bit more work will be required to transition
the `zulip::voyager` Puppet class, as that has some migration work
involved.

zerver/management/commands/initialize_production_database.py

@@ -0,0 +1,29 @@
+from argparse import ArgumentParser
+from typing import Any
+
+from django.conf import settings
+from django.core.management.base import BaseCommand
+
+from zerver.lib.server_initialization import create_internal_realm, server_initialized
+
+settings.TORNADO_SERVER = None
+
+class Command(BaseCommand):
+    help = "Populate system realm and bots for a Zulip production server"
+
+    def add_arguments(self, parser: ArgumentParser) -> None:
+        parser.add_argument('--extra-users',
+                            dest='extra_users',
+                            type=int,
+                            default=0,
+                            help='The number of extra users to create')
+
+    def handle(self, *args: Any, **options: Any) -> None:
+        if server_initialized():
+            print("Database already initialized; doing nothing.")
+            return
+        create_internal_realm()
+
+        self.stdout.write("Successfully populated database with initial data.\n")
+        self.stdout.write("Please run ./manage.py generate_realm_creation_link "
+                          "to generate link for creating organization")