CLOUDSTACK-7856: test_vpc_network_pf_rules.py - Check if httpd service is running or not, if not, start it

Signed-off-by: SrikanteswaraRao Talluri <talluri@apache.org>
CLOUDSTACK-7823: test_snapshots.py - remove test case dependency on each other

Signed-off-by: SrikanteswaraRao Talluri <talluri@apache.org>