LAM-49 Changes in apache-flink role's tasks so that init scripts run properly.

ansible/roles/apache-flink/tasks/master.yml

@@ -23,7 +23,7 @@
     template: src=flink-init.j2 dest=/etc/init.d/flink-init owner=flink group=lambda mode=0740
 
   - name: Start Apache Flink.
-    shell: /etc/init.d/flink-init start # Should use Ansible module "service: name=flink-init state=started" when the bug in version 1.9.1 is fixed.
+    shell: su - flink -c "/etc/init.d/flink-init start > /dev/null &"
     tags:
       - start