Customer survey form

[jace]

When a customer buys a ticket, they should get a survey form asking for feedback on what they'd like from the event. The email should offer three options:

1. Reply to this email to send a note to the event's manager.
2. Fill out an inline form included in the email (most email clients allow this).
3. Fill out the same form on the web incase the email client doesn't work as expected.

Email clients can typically submit a GET form without issues. Some can also submit a POST form (especially webmail clients) allowing for text area fields with long-form content. (Privacy is somewhat addressed with HTTPS.)

The content of the form should be defined by the event manager. A form constructor is a pending dependency across our projects.