(Raw)LocalFileSystem inheritance and rework

(Raw)LocalFileSystem re-implementation of the gluster shim.  Notable changes:
     * LocalFileSystem is top level class and provides user space/"local" file system request dispatch.   
     * GlusterFileSystem extends LocalFileSystem
     * GlusterVolume extends RawLocalFileSystem and is the methods to access a single gluster volume in the local user space.
     * DFS / Gluster volume directories must be specified with glusterfs:// prefix.  Local file systems SHOULD specify file://