CA-142429: The end time does not refresh when running pool audit trail report.

For pool audit trail report, when click "Run Report",
reset "_endTime" so that the end time will be re-retrieved.

Signed-off-by: Hui Zhang <hui.zhang@citrix.com>
Merge pull request #172 from xs-nanjing/CA-142429

CA-142429: The end time does not refresh when running pool audit trail report.