Add support for <input type="text">

- You can optionally pass in 'one-liner' into the_block() and get_the_block() to display an input tag instead of a textarea tag.
- Defaults to use the "editor" type.
- Post metadata structure has changed.
- Backwards compatible.

Example:
```
the_block('Name of Block', 'one-liner');
```

The post meta structure has changed. It used to be -
```
array('id-of-block' => 'name', 'id-of-another-block', ...);
```

It is now -
```
array('id-of-block' => array('name' => 'name', 'type' => 'editor'), ...);
```