Dependencies don't seem to work correctly

[ahawkins]

Hey, thanks a bunch for this project. It's been very helpful at my company. I attempted to do some schemas using dependencies. I followed this example. The current version of json-schema dsays invalid data is valid.

Given this schema:

{
  "type": "object",

  "properties": {
    "name": { "type": "string" },
    "credit_card": { "type": "number" }
  },

  "required": ["name"],

  "dependencies": {
    "credit_card": {
      "properties": {
        "billing_address": { "type": "string" }
      },
      "required": ["billing_address"]
    }
  }
}

And this data valid data

{
  "name": "John Doe",
  "credit_card": 5555555555555555,
  "billing_address": "555 Debtor's Lane"
}

And this invalid data

{
  "name": "John Doe",
  "credit_card": 5555555555555555
}

JSON incorrectly reports the invalid as valid.