tripleo-config: use become by default

The config files can be written in /etc (most of the times), so we need
sudo to write the files without permission error.

Change-Id: I68911dcec1d92def25e3b48fb1319564eda292f0

tripleo_ansible/roles/tripleo-config/tasks/main.yml

@@ -22,6 +22,7 @@
     - tripleo_config_dest is undefined
 
 - name: "Generate {{ tripleo_config_dest }} config"
+  become: true
   config_template:
     src: "{{ tripleo_config_src }}"
     dest: "{{ tripleo_config_dest }}"