Update CHANGELOG.md

Merge pull request #286 from BookOfGreg/openapi/merge

Support for some openapi3 features

Use presence on tags in travis

Update changelog

Update changelog

v2.0.6

Merge pull request #136 from ledermann/upgrade-swagger-ui-to-3-17-3

Upgrade Swagger UI to 3.17.3

Merge pull request #134 from ledermann/upgrade-swagger-ui-to-3-17-1

Upgrade Swagger UI to 3.17.1

Merge pull request #117 from imRohan/master

Fixed typos in the swagger_helper.rb file

Tweak rswag-ui.gemspec to include node_modules