Random UUID

[jmckee46]

Problem:
I had the need to use http-spec on a post using a random uuid so I can re-run the tests whenever I want. I also then needed an auth header based on the created random uuid.

Solution:
I created two new substitutions ⧈random-uuid⧈, and ⧈random-uuid-auth-header⧈. ⧈random-uuid⧈ simply creates a new random uuid. ⧈random-uuid-auth-header⧈ creates a new auth header based on ⧈random-uuid⧈ and the static password "random-uuid-password" then base64 encodes it.

This pull request also converts the tests to the -scheme and -hostname format and fixed various testing errors.

[tmornini]

I like ⧈random-uuid⧈ but I'm not a fan of ⧈random-uuid-auth-header⧈

Please make another PR with just ⧈random-uuid⧈ 😄

[jmckee46]

ok, done