VFS root creation is wrong on Windows

This may ultimately be a problem with VFS, or with WildFly.

We create our deployment root with an absolute VFS path of /content (see https://github.com/wildfly/wildfly/blob/dca817f584a24525c5a2f2f655aefed6d69466cf/server/src/main/java/org/jboss/as/server/deployment/module/DeploymentRootMountProcessor.java#L79 for details). However on Windows, we have special path handling (see https://github.com/jbossas/jboss-vfs/blob/eff9d8ae6d49e30038126304b5858c6c0937d672/src/main/java/org/jboss/vfs/VFS.java#L180 for details) which causes these paths to become absolute with a drive letter (e.g. W:/tmp/blah/foo/content/...) but only on windows. This makes writing policy files (for EAP) quite difficult, as well as just being generally wrong.