include "size" information for files/directories

With my datalad hat on, I find it very useful to know how many data files I do serve from http://datasets.datalad.org for any sub-directory/dataset -- the`PROVIDED/TOTAL` indicator in Size column. It would be nice if I could see in GIN/gogs also similar information -- currently I have no clue about total size of the dataset or for which subdirectories I did upload data (and for which forgot), see e.g. https://web.gin.g-node.org/yarikoptic/ds000001 and try to answer above question ;-)