Created todo item for embeddable resources

Should address #1
Added collection name property to HalCollection
Added ability to have additional attributes as part of collection

- A collection is also a resource
Render collections properly

- Collections are _embedded, using the $collectionName of the
  HalCollection
- Attributes should be used as the basis for the payload
Allow embedded HalItems

- Renders embedded HalItems
Allow embedded items in collections
Updated README to detail embedded resources

- only covering individual items so far
Allow setting collection name via controller
Merge branch 'feature/embedded' into develop

Allow embedding HAL resources.

Fixes #1