Cleanup after testcase running

Cleanup after testcase running

After every testcase running cleanup neutron and nova elements:
 - Allocated floating IPs (nova)
 - Created instances (nova)
 - Created images (nova)
 - Created router-subnet interfaces (neutron)
 - Created gateaway routers (neutron)
 - Created routers (neutron)
 - Created subnets (neutron)
 - Created networks (neutron)
 - Created bgpvpns (neutron)

JIRA: SDNVPN-145
JIRA: SDNVPN-148

Change-Id: Id6df004bb9d0d394e2cf39692b624607167c9a6c
Signed-off-by: tomsou <soth@intracom-telecom.com>