Moved creation of HalCollections into HalLinks

- new "createCollection()" method, which also calls a new
  "injectSelfLink()" method (copied from the ResourceController; will be
  deprecating it there after resource creation is accomplished)
Moved HalResource creation to HalLinks

- Ported over getIdentifierFromResource() logic into default
  getIdFromResource listener in HalLinks.
- Removed getIdentifierFromResource and injectSelfLink from
  ResourceController
- Created createResource() method in HalLinks, which will create a
  resource from the metadata map, if present, or else use default logic
  to do so.