Add "Verify Email" step to user registration workflow

[maxgraziano]

Problem: Current registration workflow does not validate emails making the project susceptible to spam account creation.

Solution: Add step to registration process to send an email to registering user. Requiring them to click a link in email for account to become active and allow logins. Similar process to reset password workflow.

[maxgraziano]

Per feedback at 5/14 ChiHackNight, be sure to add a Captcha for the verify workflow.