CSIT-465: Common test setup and teardown

CSIT-465: Common test setup and teardown

This test setup and teardown is aimed to be used with all functional
tests.
It does not include functionality to manipulate VMs (qemu).

Test setup includes:
- Setup all DUTs before test
- Save VPP PIDs
- Setup all TGs before traffic script
- Update All Interface Data On All Nodes

Test teardown includes:
- Show Packet Trace on All DUTs
- Show vpp trace dump on all DUTs
- Vpp Show Errors On All DUTs
- Check VPP PID in Teardown

Change-Id: Ifee0bd58b7865442c5b510852908fd8363e3c543
Signed-off-by: Tibor Frank <tifrank@cisco.com>