FEATURE: Sign Up Verification: Add a way to copy/paste verification code into the app from the email

[dzwillia]

Right now, the flow for a new user is:

1. Sign up page
2. Thanks for signing up (with a "Resend Verification Email" button)
3. Open the "Welcome" email in their email client and click the "Activate my account" button

This is essentially a "dead end" in the app as the user has to open an email and click the "Activate my account" button in the email.

A better option would be for the "Thanks for signing up page to include an input which the user could copy/paste their verification code into to continue. Obvioulsy, we would still have the "Activate my account" button in the email as well.