Now ready for review! 🎉 Thank you for your patience 🙇

• Context, API client instances now passed around as arguments (instead of being fetched from package-level)
• API client now configured from the "outside"
• FakeHTTP provides ability to stub multiple HTTP responses in a test

	initBlankContext("OWNER/REPO", "master")
	http := initFakeHTTP()

	jsonFile, _ := os.Open("../test/fixtures/prList.json")
	defer jsonFile.Close()
	http.StubResponse(200, jsonFile)

If approved, feel free to merge away in your timezone. Lots of things have moved around and interfaces changed, so apologies for the inconvenience of resolving conflicts in other branches. Let me know what you think!

Thanks @vilmibm for providing early feedback. ❤️

To figure out in followup PRs:

• ability to stub out responses from CLI child processes such as git status

I'm a little concerned about the http round tripper initialization being kind of confusing

Yes I can see how that code is a bit daunting. I'm open to exploring how we can simplify it! Basically, the http.RoundTripper interface is Go's take on middleware, and so lends itself well for dependency injection into an http.Client. I chose this path to inject a RoundTripper that returns stubs in tests, but we can also go about this different ways.