Add "sign up for emails" thing

[sinak]

Below call tool, smaller, "want to keep updated" as title, with checkbox, unchecked for EFF, plus referral codes for different orgs (FFTF, Free Press, Demand Progress, Taskforce, EFF)? Defaults to EFF.

[sinak]

Ideally I'd love to do a dropdown that lets you choose which org you want to sign up to emails from. But probably out of scope for now.