Association/Attribute `name` attribute exposed but not supported

[wadetandy]

Turns out we never actually implemented attribute remapping, even though we exposed it in configuration options.

Given an api response like:

{
  data: {
    id: '12',
    type: 'posts',
    attributes: {
      post_name: 'The Post',
      body: 'body text',
   },
   relationships: {
     the_author: {
       id: '1',
       type: 'people'
     }
  }
  // ...
}

Then the following should map correctly to those attributes both reading from and writing to the API:

@Model()
class Post extends ApplicationRecord {
  @Attr body : string
  @Attr({ name: 'post_name' }) name : string
  @BelongsTo({ name: 'the_author' }) author : Person
}