Run ferm role when letsencrypt tag is defined on provision (#1588)

Fix for: #1587

Author: zak-wearecore

server.yml

@@ -16,7 +16,7 @@
     - { role: common, tags: [common] }
     - { role: swapfile, swapfile_size: 1GB, swapfile_file: /swapfile, tags: [swapfile] }
     - { role: fail2ban, tags: [fail2ban] }
-    - { role: ferm, tags: [ferm] }
+    - { role: ferm, tags: [ferm, letsencrypt] }
     - { role: ntp, tags: [ntp] }
     - { role: users, tags: [users] }
     - { role: sshd, tags: [sshd] }