Fix for CSS copying on windows issue

It would be better with all pathing to use the Commons FilenameUtils.separatorsToSystem(String path) to be safe.  Also, that same utility has a lot of other useful methods that we could be leveraging throughout: 

A few:
normalize(String filename)  //normalize unneeded relative paths to simplify the path.  ex:  a/b/../b becomes a/b
getExtension(String filename) //gets the extension
wildcardMatch(String filename, String wildcardMatcher) //allows you to compare extensions or file names easily via wildcard