Add cbt protocol, to be able to mitigate some DDoS attacks
Add support for mac address source rules

This is necessary to parse rules generated on OpenStack Havana + Neutron + OpenVSwitch
Making it mergable:

 * Missing type definition
 * Fix failing test
 * Acceptance testing + fix parameter match
 * Renamed mac_addr to mac_source
Merge pull request #337 from damjanek/master

Add support for mac address source rules pt2
Merge pull request #388 from thias/cbt

Add cbt protocol, to be able to mitigate some DDoS attacks
(MODULES-450) Enable rule inversion

iptables has many rule arguments that may be inverted by prefixing with
an exclamation mark. This commit enables inversion for most every
property currently in the firewall provider that supports inversion by
prefixing the value with a bang+space.

Array elements must have all array elements prefixed with a bang+space
otherwise a warning will be raised, as it would look confusing to negate
a single value and then have iptables negate all of them.
Merge pull request #394 from hunner/fix_negate

(MODULES-450) Enable rule inversion