Add a mean to collect and show the Requests Events durations using Metrics  https://issues.apache.org/jira/browse/OFBIZ-5198
This has involuntary slipped in, thanks to Adrian who reviewed

git-svn-id: https://svn.apache.org/repos/asf/ofbiz/trunk@1485620 13f79535-47bb-0310-9956-ffa450edef68