Add support for ruby

[kapillamba4]

Fixes #11

[kapillamba4]

@championswimmer, bhaiya judge-worker-ruby and judge-worker-csharp docker images needs to be pushed to docker hub for travis build to pass, all tests are passing when run locally

[codecov]

Codecov Report

Merging #14 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #14   +/-   ##
=======================================
  Coverage   94.73%   94.73%           
=======================================
  Files           2        2           
  Lines          19       19           
  Branches        2        2           
=======================================
  Hits           18       18           
  Partials        1        1

Impacted Files	Coverage Δ
config.js	100% <ø> (ø)	⬆️

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