Purge Workflow Logs batch process

Code	`PurgeWorkflowLogs`
Categories	`UIRunnable`, `Schedulable`
Implementation	Batch process
Stoppable	No (single phase process)
Schedule	On the first day of the month, at 2:30 a.m.
Class	PurgeWorkflowLogs.gs

The Purge Workflow Logs batch process purges completed workflows logs. This process uses Gosu class PurgeWorkflowLogs to read the value of WorkflowLogPurgeDaysOld parameter in config.xml. The process then uses this value to determine the number of days to retain workflow logs before purging them.