Scenario tests for FWaaS

The patchset contains 6 test methods for Firewall feature.
All test methods combines several test cases.

Common preconitions for all test:
* One private network
* Router
* Two instances with floating ip assigned

Way of verifying firewall configuration:
A test try to send message via UDP/TCP from one instance
to another. To perform sending and listening the tests
use 'nc' utility. Example commands:
Listen: 'nc -l -p 5000 -s 10.0.0.10'
Send: 'echo -n "Message" | nc -w1 -p 5000 10.0.0.10 5000'
Listener instance listens on a 'fixed ip' address. Sender
sends message to a 'floating ip' address of a listener.

Tested parameters and options:
* Protocols: TCP, UDP, None (ANY)
* Actions: ALLOW, DENY
* Source IP address
* Destionation IP address
* Source port
* Destination port
* Firewall state: UP, DOWN
* Firewall policy
* Rule state: Enabled, Disabled

Works with Cirros>=0.3.3