Parse fixtures

This PR addresses a number of issues

* Adds a basic Grunt build file to the project
* Makes the href property available in Link objects
* Fixes broken JSON in the test fixtures
* Adds tests to parse the test fixtures to parse_spec.js
* Removes a cyclic require-dependency (thereby fixing a bug with embedded resources)
* Make non-hal properties available in Resource object

I also renamed some local variables - maybe I should have refrained from doing so to keep the PR more focussed. We can revert the renamings if you don't like them.

I did not yet touch the issue with the link relations that actually contain an array of link objects instead just a single link object. I would like to discuss how such an array of links should be made available to client code conveniently. I'll open a issue for that.