Remove the HTTP API

[Gallaecio]

Removes the HTTP API, as it adds complexity to the code base without adding much value.

Part 1 of 2 of #63

Closes #111

[codecov]

Codecov Report

Merging #125 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #125   +/-   ##
=======================================
  Coverage   87.78%   87.78%           
=======================================
  Files          11       11           
  Lines         475      475           
  Branches      103      103           
=======================================
  Hits          417      417           
  Misses         52       52           
  Partials        6        6

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[kmike]

Let's remove it - thanks @Gallaecio! Also, thanks @cathalgarvey for the idea.
If there is an interest, code can be easily moved out of extruct, to a separate repo.