mod_http_upload_quota: Omit info message

The mod_http_upload_quota module attempts to delete a directory whenever
it removes a file from that directory.  However, if thumbnail creation
is enabled, directories will often contain two files.  Therefore, don't
log an info (but only a debug) message if directory removal fails.

src/mod_http_upload_quota.erl

@@ -332,7 +332,7 @@ del_file_and_dir(File) ->
 	    ok ->
 		?DEBUG("Removed ~s", [Dir]);
 	    {error, Error} ->
-		?INFO_MSG("Cannot remove ~s: ~s", [Dir, ?FORMAT(Error)])
+		?DEBUG("Cannot remove ~s: ~s", [Dir, ?FORMAT(Error)])
 	  end;
       {error, Error} ->
 	  ?WARNING_MSG("Cannot remove ~s: ~s", [File, ?FORMAT(Error)])