Elements of a Hypermedia Message Document

Per issue #4, this is the first draft of this document describing the elements of a hypermedia message. It is all open for discussion, and I'd be happy to change anything. Below are some discussion items.

- [x] 1. Is the categorization of transitions helpful?
- [x] 2. Should this include the concept of curies or prefixes?
- [x] 3. Is the concept of anonymous links and actions helpful?
- [x] 4. Does it make sense to include embedded resources under transitions?
- [x] 5. How do we address more complex attributes? Ones that may include arrays of objects in JSON or nested elements in XML?

Once we come to a consensus, we can merge it into the repo. Thanks!
@smizell I don't think ALPS crosses that divide. It just defines the semantics. The implementation details are left to the implementer of the protocol. If they do not follow the guidlelnes of the protocol, then you are stuck. But I think this highlights an interesting question on whether you can rely on a GET to be safe. It should be. There is nothing in a relation type to indicate this and nothing concrete in the verb. This is an interesting case for the need for a profile, but ALPS does not ATM make a MUST. It just gives examples of the appropriate verb.