Make the gem installation silent, since it always produce "changed"

mscherer · mscherer · commit 1c12e2a03e77 · 2016-04-19T10:47:14.000+02:00
diff --git a/tasks/main.yml b/tasks/main.yml
@@ -54,6 +54,7 @@
   become: yes
   become_user: '{{ builder_username }}'
   become_method: 'su'
+  changed_when: False
 
 - set_fact:
       rsync_url: ""
