implement the postman button

[travi]

• https://www.getpostman.com/integrations/run-button
• http://blog.getpostman.com/2016/03/10/run-button-is-live/
• http://www.getpostman.com/docs/run_button

maybe https://www.npmjs.com/package/hapi-postman

[travi]

importing https://api.travi.org/swagger into postman does not include the hostname

[travi]

http://blog.tdwright.co.uk/2018/10/27/mega-mash-up-api-testing-with-postman-azure-devops-and-randomuser-me/