[#2097] Use simplified WMI source for peak memory usage monitoring.

Problem
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Unable to run tests on Windows 7 64bit after latest update. Looks like there is a compatibility issue with the WMI.

Changes
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Use a basic source for peak working set values `Win32_Process`. Will report values in Kilobytes with the exception of Windows XP, where the value is in bytes.

How to test
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reviewers @adiroiban 

Please check that code looks ok. Thanks. I've checked 2003, 2008 and XP and the values reported by master and this branch match.