CA-90845 : XenCert functional iscsi test fails to detect LUNs and passes...

.... Multiple issues in Functional tests

There were more then one problems blocking the successful run of Functional tests:
1. StorageHandler.py - Filepath was being calculated incorrectly
2. Diskdatatest binary:
a. Calculate time taken correctly in write_testpattern and verifytestPattern
b. In Main - stdout should just print estimatetime in last line (no string)
3. StorageHandlerUtil: FindDiskDataTestEstimate : Calculate totaltime correctly