SchemaValidator not returning correct invalid additionalProperties

I was noticing the SchemaValidator will just return the name of the first property for an object that has invalid additional properties. For example, with the schema snippet:

```
'contact' => [
    'type' => 'object',
    'additionalProperties' => false,
    'location' => 'json',
    'properties' => [
        'email' => [
            'type' => 'string'
        ],
        'name' => [
            'type' => 'string'
        ]
    ]
]
```

Passing in the following parameters:
['email' => 'example@address.com', 'invalidParam' => 'random', 'anotherInvalid' => 'random]

Returns the a ValidationException reporting only 1 validation error for the wrong property:
Validation errors: [contact][email] is not an allowed property.

This pull request should cause the validation errors to be:
[contact][invalidParam] is not an allowed property
[contact][anotherInvalid] is not an allowed property