Identify os architecture on windows 2003, 2008, 2012

Previous tests relied on wmi os osarchitecture property, which is not
present on Windows 2003.  Now we check osarchitecture first, and use
its result if successful.  If that attempt fails we fall back to
grepping the wmi os name property for an x64 string.
Merge pull request #52 from jpartlow/issue/master/determine_windows_arch_for_2003_through_2012

Identify os architecture on windows 2003, 2008, 2012