Applied patch from jira issue - OFBIZ-5766 - Error when adding/modifying a task to a Production Run - field type error.
Thanks Guillaume Sigoigne for reporting the issue, Thanks Divesh for providing the patch for this issue. 

git-svn-id: https://svn.apache.org/repos/asf/ofbiz/trunk@1639880 13f79535-47bb-0310-9956-ffa450edef68