Rework GHResponse to incorporate useful data on unhappy path

[BenFradet]

partially addresses #363 , cc @dcsobral

[codecov]

Codecov Report

Merging #367 into master will increase coverage by 0.18%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #367      +/-   ##
==========================================
+ Coverage   92.45%   92.64%   +0.18%     
==========================================
  Files          24       23       -1     
  Lines         530      530              
  Branches        0        1       +1     
==========================================
+ Hits          490      491       +1     
+ Misses         40       39       -1     

Impacted Files	Coverage Δ
...ub4s/src/main/scala/github4s/GithubResponses.scala	100.00% <ø> (ø)
...ub4s/src/main/scala/github4s/http/HttpClient.scala	93.75% <100.00%> (+0.20%)	⬆️
.../scala/github4s/interpreters/AuthInterpreter.scala	100.00% <100.00%> (ø)

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[juanpedromoreno]

👍