#31 adds proper serialize behavior

[makepanic]

tries to fix #31 Most of the code is inspired by the json-serializer and json-api-serializer serialize method.
They're a couple open questions:

• how should we handle links in the serializer? We could add a flag where the method adds the metadata links to the serialized document
• are there any cases that should be tested except the ones in the new serialize-test.js?

[bantic]

Cool, thanks for putting this together. I am going to look over it tomorrow. My instinct is that, since HAL doesn't specify outgoing formatting, we should defer this entirely to Ember Data. A HAL backend could theoretically accept any sort of incoming payload; the APIS I have worked with have not expected to get incoming HAL-formatted responses (only to send outgoing HAL-formatted JSON), but maybe there are some that do.

[makepanic]

What about providing a mixin that contains the serialize method to serialize to a HAL document? (or providing a serializer that exports the current one with the HAL serialize method applied)

I think it's useful to provide "HAL in, HAL out" support out of the box or make it really easy to add.

[mixonic]

@makepanic HAL has no out, it is specifically designed as a read-only format only. That there is no prescription for making changes is a limitation of the spec.

So to be clear, this change to HAL-9000 does not align us more closely, or move us further away from, the actual spec. Our decision is completely our own here.