Fix bare variables in with_* loops

Fixes #49

tasks/plugins.yml

@@ -12,7 +12,7 @@
 
   - name: Ensure any remote plugins defined are present
     shell: sensu-install -p {{ item }}
-    with_items: sensu_remote_plugins
+    with_items: "{{ sensu_remote_plugins }}"
     changed_when: false
     when: sensu_remote_plugins > 0
 
@@ -31,7 +31,7 @@
       group: "{{ sensu_group_name }}"
     when: "'{{ item }}' in sensu_available_checks.stdout_lines"
     with_flattened:
-      - group_names
+      - "{{ group_names }}"
     notify: restart sensu-client service
 
   - name: Deploy handler plugins