No CAPTCHA for ENS users

[ligi]

Idea came after conversations with @roninkaizen and @skylenet

For ENS we could skip the captcha - just need to find a good UX for it (maybe a 2 step process - first the address - then (if needed) the proof of humanity.)
Could also be an option (via configuration) to fight people draining faucets with bots (btw.: if anyone reading this is an operator of some - would really love to talk to you to understand the motives) if this is the only option - so you can only get funds from the faucet with an ENS name - this will make it a really hard time for bots.