provision: Fix missing dependency on unzip.

Because this is often installed by default, we hadn't noticed that our
Slack importer doesn't run without it.

Thanks to Ray Kraesig for the report.

puppet/zulip/manifests/app_frontend_base.pp

@@ -8,6 +8,8 @@ class zulip::app_frontend_base {
   $web_packages = [
     # Needed to access our database
     "postgresql-client-${zulip::base::postgres_version}",
+    # Needed for Slack import
+    'unzip',
   ]
   zulip::safepackage { $web_packages: ensure => 'installed' }
 

tools/lib/provision.py

@@ -147,6 +147,7 @@ COMMON_DEPENDENCIES = [
     "gettext",              # Used by makemessages i18n
     "curl",                 # Used for fetching PhantomJS as wget occasionally fails on redirects
     "moreutils",            # Used for sponge command
+    "unzip",                # Needed for Slack import
 ]
 
 UBUNTU_COMMON_APT_DEPENDENCIES = COMMON_DEPENDENCIES + [