Allows using any.rename() and any.default() together

Example:

With this Joi object: `{ foo: Joi.string().rename('foo2').default('test') }`
And the input value: `{}`

The validation should output:
```
{
  foo : 'test',
  foo2: 'test'
}
```

But was outputting:

```
{
  foo: 'test',
  foo2: undefined
}
```