Spike public lesson and event site

Based on #9

## Home page

![homepage](https://f.cloud.github.com/assets/623/463154/ba6fb4c8-b52d-11e2-81fe-04dc9d530c0a.png)

## Lessons

![lessons](https://f.cloud.github.com/assets/623/463155/c03ce524-b52d-11e2-96ea-a14e17a471a7.png)

## Lesson Without Upcoming Event

![lesson](https://f.cloud.github.com/assets/623/463156/cf805160-b52d-11e2-99eb-7989985df7ad.png)

## Lesson With Upcoming Event Registration Not Yet Open

![lesson-with-upcoming-event-registration-not-yet-open](https://f.cloud.github.com/assets/623/463157/da59091a-b52d-11e2-8b5a-b9d946bc08e6.png)

## Lesson With Upcoming Event Registration Open

![lesson-with-upcoming-event-registration-open](https://f.cloud.github.com/assets/623/463158/e3746cf6-b52d-11e2-88e8-f65b6348e083.png)

## Registration Open Html Email

![registration-open-html-email](https://f.cloud.github.com/assets/623/463246/ad3f21ba-b543-11e2-865c-615e15eb9299.jpg)

## Registration Open Text Email

![registration-open-text-email](https://f.cloud.github.com/assets/623/463247/cf9c4490-b543-11e2-9cee-7b88f88966ee.jpg)

## Registration Confirmed Html Email

![registration-confirmed-html-email](https://f.cloud.github.com/assets/623/463248/d721479c-b543-11e2-962b-790e5a4c9776.jpg)

## Registration Confirmed Text Email

![registration-confirmed-text-email](https://f.cloud.github.com/assets/623/463249/ddb4b382-b543-11e2-84bd-e7881ff12915.jpg)

- [x] Basic Lesson model.
- [x] Basic Event model.
- [x] Lesson importer.
- [x] Event importer.
- [x] Lessons page.
- [x] Add upcoming event logic to lesson page.
- [x] Add registration logic to lesson page.
- [x] Basic homepage with upcoming event.
- [x] Notify me of event email.
- [x] Register for event email.
- [x] Lesson and Event import rake task.

- [x] Fix date and time UI to use correct timezone.
- [x] Use image from repo for lesson view.
- [x] Finish PR with screenshots.