Merge branch 'fail2ban' into 'master'

Adding fail2ban role

See merge request hpc-team/ansible_cluster_in_a_box!257

roles/fail2ban/handlers/main.yml

+---
+- name: restart fail2ban
+  service: name=fail2ban state=restarted

roles/fail2ban/tasks/main.yml

+---
+- name: Install fail2ban on Red Hat system
+  yum:
+    name: 
+    - fail2ban-server
+    - fail2ban-systemd
+    - fail2ban-sendmail
+    state: present
+  become: true
+  become_user: root
+  when: ansible_os_family == "RedHat"
+
+- name: Copy jail.conf.j2 to /etc/fail2ban/jail.conf
+  template:
+    src: jail.conf.j2
+    dest: /etc/fail2ban/jail.conf
+    mode: 0644
+    owner: root
+    group: root
+  become: true
+  become_user: root
+  notify:
+    - restart fail2ban
+
+- name: Enable fail2ban service
+  systemd:
+    name: fail2ban
+    enabled: yes
+    state: started
+  become: true
+  become_user: root