Feature Request: `capitalize` filter
Feature request for a 'capitalize' filter, which would behave as `text-transform: capitalize` style does.

Input:
```
{
  name: {
    first: 'sally',
    last: 'ferguson'
  }
}
```

Filter:
```
{name.first | capitalize} {name.last | capitalize}
```

Output:
```
Sally Ferguson
```

  