Properly root log path in logstash gearman client.

* modules/openstack_project/files/logstash/log-gearman-client.py:
BASE_LOG_PATH is a relative dir and is not rooted. Provide the root '/'
when constructing the source URL for the gearman workers.

Change-Id: I8fcfa19b048019398ffd370d74c271b9656a8688
Merge "Properly root log path in logstash gearman client."