Windows Support: Testing Suite integration

Broaden support for execution of the test suite
on Windows.
General bug and review fixups

share/spack/qa/windows_test_setup.ps1

@@ -8,4 +8,4 @@ foreach {
         $v = $_.split("=")
         [Environment]::SetEnvironmentVariable($v[0], $v[1])
     }
-}
+}