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
Er indeed that should be in the 'else' branch.

But in any case, calling `updated_by_last_action` is how you tell Chef that this resource actually got something done, which is what Chef relies on to trigger notifications to other resources that might be watching the current one (you know, the whole `notifies` mechanism). So it's pretty important to do that correctly.