Update README.md

Removing check boxes for `Arbitrary` conformance and `OpenAPI` integration. Both of these "features" are maintained in separate libraries.

Merge pull request mattpolzin#18 from mattpolzin/feature/match-jsonap…

…i-naming

Feature/match jsonapi naming

clarifying name change in tests. update documentation around entity d…

…irect subscript accessor

Merge pull request mattpolzin#17 from mattpolzin/swift-5

Default to Swift version 5.0 and Swift Tools version 5.0

Update cocoapods version, update readme to mention cocoapods support.

A bit more clarification/correction

Remove Playground page that used the OpenAPI support that has now mov…

…ed into its own repository.

update linuxmain

fix open API playground.

Fix Include OpenAPI support. Fix bug with single include being consid…

…ered 'OneOf' even though that is an overcomplication of the schema. Add tests for single include type and two include types on document