Strip subscription path from created filename; same for cache file

When a file was created, it would be created appending the subscription path to the physical directory.  So if you subscribe to /uploads/files and your physical directory is /tmp/foo, files would be created as /tmp/foo/uploads/files/...  This change uploads files to /tmp/foo/...

Added changeset to fix server sending files already on the client.  The .cache file is written with basenames of the file, whereas the lookup prepends the vpath.  Changed the lookup to remove vpath.