Wormhole HAL parsing and Collection support

This PR:

* Supports round tripping the HAL-based Wormhole data. The sample data I have does not have any Hale super-set features so a separate serializer is not yet needed. The test code here proves that a Wormhole response can now be fully parsed.
* Added ```type``` support for ```_links``` in HAL
* Support for Collections in HAL/Hale and the Representor. Uses the ```items``` embedded resource convention for HAL/Hale.

@mdsol/hypermedia-team Please review and merge. I will continue developing on this branch in the meantime - any things that need addressing can go in the next PR.