Merge pull request mattpolzin#80 from mattpolzin/update-podspec-for-v-4

update podspec file for v 4

Merge pull request mattpolzin#72 from mattpolzin/change-course-slightly

Change course slightly

Merge pull request mattpolzin#71 from mattpolzin/bugfix/expose-ID-pub…

…licly

Bugfix/expose id publicly

Merge pull request mattpolzin#70 from mattpolzin/feature/swift-identi…

…fiable

Add Swift Identifiable conformance

Merge pull request mattpolzin#69 from mattpolzin/filter-relatives

Add filtering of relatives to CompoundResource

Merge pull request mattpolzin#68 from mattpolzin/update-swift-version…

…-badge

Update README.md

Add abstraction points around single and many resource bodies that ex…

…pose values.

Merge pull request mattpolzin#65 from mattpolzin/feature/add-initiali…

…zers

Add some convenience initializers

A bit more test coverage for MetaRelationship and a note at the top o…

…f a now-confusingly-named section in the documentation.

update README to refer to the 4.0 alpha