Previously we use tab spaces for indent in java and c sources,
while we use 4 spaces for indent in python sources, but it is
sometimes confusing.
This patch expands all tab spaces to 4 spaces, to use 4 spaces
for general way to indent.
Bonus:
This patch also removes trailing white spaces.
Change-Id: I1b9e7688d606c0da1bc015b1a4d396d19f4dc18a
2fdd244dce