Added ferm check in wowza setup

roles/wowza/tasks/main.yml

@@ -108,9 +108,15 @@
       find /usr/local/WowzaStreamingEngine/logs/ -type f -mtime +{{ wowza_logs_retention }} -delete
 
 # FIREWALL
+- name: check ferm
+  command: which ferm
+  register: ferm_exists
+  ignore_errors: True
 
 - name: firewall
-  when: wowza_firewall_enabled
+  when:
+    - ferm_exists
+    - wowza_firewall_enabled
   vars:
     ferm_rules_filename: "{{ wowza_ferm_rules_filename }}"
     ferm_input_rules: "{{ wowza_ferm_input_rules }}"