Indicate pseudo-folders in containers panel

The column that shows size of Objects is empty for pseudo folders.
We now indicate that this is a pseudo-folder.
Column does not have a column header so should not be confusing.
Also, show the size if the object is of size 0, (thanks Tihomir)

Closes-Bug: #1260859
Change-Id: I1ac233f5b964befa3d4f36c9a3d309383d691d28