Login templates

Basic blocks, specifically fully working login, registration, image, and content blocks. Specified blocks are working except for:
- I think the CSS needs moved. 
- Default fixtures.
- Tests.
- Easy to use admin.

Please review.

**Important Note**: All html is assume safe. This is probably not non-very-very-trusted user friendly.
What about sending an empty response (or looking up a more appropriate HTTP status code) and checking content (or status code)? Something like:
```python
response = block.handle_post(request)
if response.conent:
    return response
```

Accomplishes the same thing, requires no documentation, isn't considered abuse.