Windows file names don't work correctly

[hsolbrig]

There are a couple of spots in the utility code that mistakenly see the colon in a windows file name (c:\foo\bar...) as a URL instead of a file name. We also need to use the Unix file name conventions when adding @base and the like into the turtle parser. Note that the windows_bug branch has a first approximation of one of the fixes.

[] bug fixes in [] add windows VM to the test harness