Set more precise Kibana timestamp format.

* modules/kibana/files/config.rb: The Kibana timestamp format we were
using did not include milliseconds. Change the format to
'yyyy-mm-dd\'T\'HH:MM:ss.l' to include milliseconds in the time field.

Change-Id: I6d812d5ee3f2b778a1adccf950f5423584ad69cf
Reviewed-on: https://review.openstack.org/27752
Reviewed-by: matthew-wagoner <matthew.wagoner@hp.com>
Approved: James E. Blair <corvus@inaugust.com>
Reviewed-by: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins