Support publishing blog posts via the API

[oubiwann]

Tasks:

• create add-post (this is the Blogger insert: https://developers.google.com/blogger/docs/3.0/reference/posts/insert
• add support for representing post resources as edn
• add edn->json function
• test against staging blog

[oubiwann]

Full post resource data structure:

{
  "kind": "blogger#post",
  "id": string,
  "blog": {
    "id": string
  },
  "published": datetime,
  "updated": datetime,
  "url": string,
  "selfLink": string,
  "title": string,
  "titleLink": string,
  "content": string,
  "images": [
    {
      "url": string
    }
  ],
  "customMetaData": string,
  "author": {
    "id": string,
    "displayName": string,
    "url": string,
    "image": {
      "url": string
    }
  },
  "replies": {
    "totalItems": long,
    "selfLink": string,
    "items": [
      comments Resource
    ]
  },
  "labels": [
    string
  ],
  "location": {
    "name": string,
    "lat": double,
    "lng": double,
    "span": string
  },
  "status": string
}

[oubiwann]

Obviously, we won't need replies in the post ...

[oubiwann]

Sadly, this is not doable with service-based creds; this will require reworking things to use oauth2 (total PITA).

Might be worth it to offer service-based for read-only ops, and oauth2 for write opts.