Add git and iptables to the list of packages

1) When doing an upper branch upgrade test (anything above Ocata), we
clone previous branch, and run a playbook that targets this previous
branch. It's not possible to merge anything with the upgrade job
failing.

2) The upgrade jobs are currently failing in neutron, because pip install
in the role, for the developer mode, requires git and pip installed
INSIDE the container. We therefore need to add git to the list of packages
to install [1]

3) Similarily, iptables need to be installed on all the agents, so
we add it to the list of the packages to install. However, it's
also needed before the first neutron role executes in an upgrade,
and therefore needs an edit in the play calling the previous role:
tests/test-install-previous-neutron.yml

[1]: ```
Collecting neutron from git+https:
//git.openstack.org/openstack/neutron@stable/pike#egg=neutron
(from -c /opt/developer-pip-constraints.txt (line 1))
Error [Errno 2] No such file or directory while executing command
git clone -q https://git.openstack.org/openstack/neutron
  /tmp/pip-build-Lk_L35/neutron
Cannot find command 'git'
```

Change-Id: I1edfae74fc62d523d670bf5932587aa6626512d2
Co-Authored-By: Manuel Buil <mbuil@suse.com>

tests/test-install-previous-neutron.yml

@@ -55,6 +55,11 @@
         search_regex: OpenSSH
         delay: 1
 
+    - name: Install iptables
+      package:
+        name: iptables
+        state: present
+
     - name: Add iptables rule for communication w/ metadata agent
       command: /sbin/iptables -t mangle -A POSTROUTING -p tcp --sport 80 -j CHECKSUM --checksum-fill
 

vars/main.yml

@@ -34,6 +34,9 @@ neutron_package_list: |-
   {% if neutron_services['neutron-vpnaas-agent']['group'] in group_names and neutron_vpnaas | bool %}
   {% set _ = packages.extend(neutron_vpnaas_distro_packages) %}
   {% endif %}
+  {% if neutron_developer_mode | bool %}
+  {%   set _ = packages.extend(neutron_developer_mode_distro_packages) %}
+  {% endif %}
   {{ packages }}
 
 # Set the Calico Felix agent executable destination path

vars/redhat-7.yml

@@ -29,6 +29,9 @@ neutron_distro_packages:
   - radvd
   - which
 
+neutron_developer_mode_distro_packages:
+  - git-core
+
 neutron_lxb_distro_packages:
   - bridge-utils
 

vars/ubuntu-16.04.yml

@@ -31,10 +31,14 @@ neutron_distro_packages:
   - dnsmasq-utils
   - ebtables
   - ipset
+  - iptables
   - iputils-arping
   - keepalived
   - radvd
 
+neutron_developer_mode_distro_packages:
+  - git-core
+
 neutron_lxb_distro_packages:
   - bridge-utils