restClient should format http response data consistently for GET_* request types

[benglass]

I believe there is a bug in the way convertHTTPResponseToREST is implemented as it does not attempt to format that from GET_ONE requests in the same way that data from GET_LIST requests are formatted.

To reproduce the issue, go directly to an edit page for a resource without coming from the list page (so the item wont be in the store already from the list view), which will trigger it to be loaded via GET_ONE.

h2. What convertHTTPResponseToREST does now

1. GET_LIST, GET_MANY_REFERENCE: Transforms response.data array elements from JSON API format of { type: 'books', id: 4, { attributes: { name: 'foo' } } to { id: 4, name: 'foo' }. It also translates relationships from the JSON API format of { author: { data: { type: 'people', id: 4 } } } to { author: 4 }
2. GET_MANY: Transforms response.data array elements in the same way as GET_LIST, GET_MANY_REFERENCE handling but does not touch relationships
3. GET_ONE: Does no transformation on response.data

I believe this behavior causes a bug where data loaded by GET_ONE is a different shape in the store than data loaded by GET_LIST/GET_MANY. See screenshot below showing store data in different shapes.

I think that response.data should probably always be transformed in the same way, from a JSON-API representation that includes attributes, relationships, etc. to a plain old javascript object. This PR starts in that direction, but can you weigh in on whether my understanding here seems correct and this direction makes sense?