Compile locale to be able to change language

mo file need to be compiled in order to be able to change the language
of the dashboard.

Change-Id: Ie26496b7abeb3fc7278c00be28f6ac476dffb2eb
Closes-Bug: #1611073

tasks/horizon_post_install.yml

@@ -103,6 +103,16 @@
   notify: Restart apache2
   when: horizon_customization_module is defined
 
+- name: Compile messages for translation
+  command: "{{ horizon_bin }}/horizon-manage.py compilemessages"
+  args:
+    chdir: "{{ horizon_lib_dir }}/{{ item }}"
+  with_items:
+    - horizon
+    - openstack_dashboard
+  tags:
+    - horizon-configs
+
 - name: Collect and compress static files
   command: "{{ item }}"
   become: yes