Check if sensu_available_checks is skippeded

I think this might resolve https://github.com/sensu/sensu-ansible/issues/194

tasks/plugins.yml

@@ -40,7 +40,10 @@
     mode: 0755
     owner: "{{ sensu_user_name }}"
     group: "{{ sensu_group_name }}"
-  when: "sensu_available_checks is defined and item in sensu_available_checks.stdout_lines"
+  when: 
+    - sensu_available_checks is defined 
+    - sensu_available_checks is not skipped
+    - item in sensu_available_checks.stdout_lines"
   with_flattened:
     - "{{ group_names }}"
   notify: restart sensu-client service