Compatibility with TeamCity Windows version

[linda91hansson]

First of all, thank you for a very useful plugin.

We are using Team City on a Windows server and I noticed that the plugin does not seem to preserve the folder structure when uploading the artifacts to S3, i.e., instead of actual folders we get a one-level structure with file names like ApplicationName\Content\Site.css.

I changed the File.Separator to "/" in the getChildren function in ArtifactUploader.scala and that seems to have fixed the problem. Should this cause any issues that you know of?