Ensure firewalld is installed and Docker launcher after firewalld

Some CentOS 7 hosts may not have firewalld installed.
We shouldn't expect it to be, but should ensure by ourselves that it is.

Docker likes to mess around with iptables forwarding rules,
so it ought to start after firewalld.

roles/matrix-server/tasks/setup_base.yml

@@ -23,15 +23,16 @@
     - bash-completion
     - docker-ce
     - docker-python
+    - firewalld
     - ntp
   when: ansible_distribution == 'CentOS'
 
-- name: Ensure Docker is started and autoruns
-  service: name=docker state=started enabled=yes
-
 - name: Ensure firewalld is started and autoruns
   service: name=firewalld state=started enabled=yes
 
+- name: Ensure Docker is started and autoruns
+  service: name=docker state=started enabled=yes
+
 - name: Ensure ntpd is started and autoruns
   service: name=ntpd state=started enabled=yes