Add Docker publish steps

[gabeduke]

Fixes #17

[codecov]

Codecov Report

Merging #18 into develop will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop      #18   +/-   ##
========================================
  Coverage    67.44%   67.44%           
========================================
  Files            1        1           
  Lines           43       43           
========================================
  Hits            29       29           
  Misses           9        9           
  Partials         5        5

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