Page objects now contain url

Page objects now return the web address of the page in the url key.

JSON

{
  "object": "page",
  "id": "251d2b5f-268c-4de2-afe9-c71ff92ca95c",
	"created_time": "2020-03-17T19:10:04.968Z",
	"last_edited_time": "2020-03-17T21:49:37.913Z",
  "parent": {
    "type": "database_id",
    "database_id": "48f8fee9-cd79-4180-bc2f-ec0398253067"
  },
  "archived": false,
  "url": "https://www.notion.so/Avocado-251d2b5f268c4de2afe9c71ff92ca95c",
  "properties": {
    "Name": {
      "id": "title",
      "type": "title",
      "title": [
        {
          "type": "text",
          "text": {
            "content": "Avocado",
            "link": null
          },
          "annotations": {
            "bold": false,
            "italic": false,
            "strikethrough": false,
            "underline": false,
            "code": false,
            "color": "default"
          },
          "plain_text": "Avocado",
          "href": null
        }
      ]
    }
  }
}

This impacts endpoints that return page object: the pages endpoints and query database endpoint.