Use /usr/sbin/nologin as login shells for vmail and znc users

roles/ircbouncer/tasks/znc.yml

   group: name=znc state=present
 
 - name: Create znc user
-  user: name=znc state=present home=/var/lib/znc system=yes group=znc
+  user: name=znc state=present home=/var/lib/znc system=yes group=znc shell=/usr/sbin/nologin
 
 - name: Copy znc init file into place
   copy: src=etc_init.d_znc dest=/etc/init.d/znc mode=0755

roles/mailserver/tasks/dovecot.yml

   group: name=vmail state=present gid=5000
 
 - name: Create vmail user
-  user: name=vmail group=vmail state=present uid=5000 home=/decrypted
+  user: name=vmail group=vmail state=present uid=5000 home=/decrypted shell=/usr/sbin/nologin
 
 - name: Ensure mail domain directories are in place
   file: state=directory path=/decrypted/{{ item.name }} owner=vmail group=dovecot mode=770