Add dependencies tag to some tasks where it was missing

roles/ircbouncer/tasks/znc.yml

   apt: pkg={{ item }} state=installed
   with_items:
     - znc
+  tags:
+    - dependencies
 
 - name: Create znc group
   group: name=znc state=present

roles/monitoring/tasks/collectd.yml

 - name: Install collectd
   apt: pkg=collectd state=installed
+  tags:
+      - dependencies
 
 - name: Copy collectd configuration file into place
   template: src=etc_collectd_collectd.conf.j2 dest=/etc/collectd/collectd.conf