Feature/metadata links

@mszenher Please review and merge after merging PR https://github.com/mdsol/crichton/pull/18.

This PR refactors the YAML resource descriptor links for encapsulation and adds accessors for metadata links.

All specs passing:

Once other PRs are merged, code coverage will be better.

Finished in 3.77 seconds
242 examples, 0 failures, 1 pending
Coverage report generated (99.59%) covered.