using standard unix postfixes add unit test for display
also change doc for memory usage display change
for example GiB will be GB
Signed-off-by: Sun Jianbo <wonderflow@zju.edu.cn>
We now advise people to configure docker group and
add to sudo. Mac shouldn't use sudo. Removed sudo
from command examples. Left in installation to be removed
in installation doc sweep -- removing requires finer
grain control.
Signed-off-by: Mary Anthony <mary@docker.com>
