conf: Enable test reports store in a directory per test run.
conf: Enable test reports store in a directory per test run.

Example output:
===============
ls test-reports/test-run-20180608101142/
20180608101142.log
TEST-testcases.OpTestFlash.FSPFWImageFLASH-20180608101142.xml
Kernel_dmesg_log_Fri_Jun__8_10:12:10_2018.log
TEST-testcases.OpTestFlash.OpalLidsFLASH-20180608101142.xml
Opal_msglog_Fri_Jun__8_10:12:09_2018.log
TEST-testcases.OpTestFlash.PNORFLASH-20180608101142.xml
TEST-testcases.OpTestFlash.BmcImageFlash-20180608101142.xml
TEST-testcases.OpTestSensors.OpTestSensors-20180608101142.xml

Signed-off-by: Pridhiviraj Paidipeddi <fd8ea14509c256cbd04eaa4ee745a213945e70a1@linux.vnet.ibm.com>

open-power/op-test-framework,open-power/op-test-framework,open-power/op-test-framework