Use yaml.Unmarshal for swagger.yaml (goadesign#1932) (goadesign#1936)

* Use yaml.Unmarshal for swagger.yaml

* Add jsonToYAML to goagen/gen_swagger/generator.go

* Update jsonToYAML

Release v1.4.0

Properly update version to 1.3.1

release v1.3.0

release v1.2.1

Release v1.2.0

Fix merge conflict with README

Bump version to 1.0.0