Option for generating Postman collection file

[makotogitdev]

This PR introduces an option to generate a Postman collection JSON file. By allowing the option, it saves time on creating requests manually in Postman or using yet another gem and DSL to generate a file for it. The intention of this PR is to provide initial minimal support for Postman and add-on nice-to-have features later. There probably are real world situations that I may not have accounted for in this change so that's why I mentioned in README that Postman support is in Alpha.

Some notes:

• Since Postman is meant to be interactive, I did not pull in the test values for parameters and responses.
• For parameters that for request body, they will be listed under the description on each request.
• For parameters that are for URL query params, their descriptions will also directly be listed when click on Params button in Postman
• It is assumed that the user will define authorization and application URL at a parent level

[dcluna]

@makotogitdev Thanks for that! I've been looking for a similar solution for a while. I'm a bit confused about this:

Since Postman is meant to be interactive, I did not pull in the test values for parameters and responses.

When you generate the response collection in Postman, they are imported under that request as Examples. So there is some value in including them in the generated file - especially when you're trying to record an example for a scenario that is hard to set up.