Content mutations

[bdunogier]

Adds support for creating, updating and deleting content over GraphQL.

For each content type:

• two mutations are defined create{ContentType} (createBlogPost, createImage, ...) and update{ContentType} (updatePlace, updateVideo, ...)
• two input types are defined, one for each operation: updateArticleInput, createImageInput

Usage:

mutation CreateMyBlogPost
{
  createBlogPost(
    parentLocationId: 216,
    input: {
      title: "The post's title",
      author: [
        {name: "Bertrand Dunogier", email: "noemail@ez.no"}
      ],
      body: {
        format: html,
        input: "<h1>title</h1><p>paragraph</p>"
      }
    } 
  ) {
    _info { id mainLocationId }
    title
    body { html5 }
  }
}

[bdunogier]

Moved to https://github.com/ezsystems/ezplatform-graphql/pull/4.