Init a slice with length 0, otherwise it will init
it with capability as length and the following append
operation will append the value and there will be
"length" zero value in front.

Signed-off-by: Fupan Li <lifupan@gmail.com>

For some hypervisor based containers, it would take much longer
time to create a pod, thus it's better expand the tiemout value
from 2 to 5 to avoid timeout errors.

Signed-off-by: Fupan Li <lifupan@gmail.com>

Add a testcase for measuring the time of creating a pod
and container.

Signed-off-by: Fupan Li <lifupan@gmail.com>