add liveness probe, fix readiness prob exec

add liveness probe, fix readiness prob exec

liveness and readiness probes may run script with
arguments, ports and volumes are optional instead
of mandatory, test_tasks.py accept ports[] and
volumes[]
fix the issue of labels which are logner than 63

Issue-ID: DCAEGEN2-1126
Change-Id: Id2f893adc300bf508c0512a51b3665872d36f674
Signed-off-by: Jason Luo <cl4531@att.com>