Threat control LWRP

Cf. first commit and README changes:

Add a threat_control LWRP, allowing to whitelist/blacklist IPs on CloudFlare
* Stores last action in a node attribute cache, CF API is only called once per day, or if status changes
* IP attribute defaults to current's node IP address
Go tell that to Python PEP-8'ers following a spec which originated in 2001. ;-)
Do you have more up-to-date guidelines saying otherwise?