Fix versioning for push event

[webbertakken]

This PR:

• Fixes fetch command not always fetching enough refs to relate head to a tag
• Adds test coverage for versioning
• Adds output for debug and error output in System.run
• Removes dependency on Input model for getting relative path
• Removes unnecessary output from tests and execution

[codecov]

Codecov Report

Merging #83 into master will increase coverage by 8.77%.
The diff coverage is 94.44%.

@@            Coverage Diff             @@
##           master      #83      +/-   ##
==========================================
+ Coverage   85.14%   93.92%   +8.77%     
==========================================
  Files          14       14              
  Lines         202      214      +12     
  Branches       39       43       +4     
==========================================
+ Hits          172      201      +29     
+ Misses         27       13      -14     
+ Partials        3        0       -3     

Impacted Files	Coverage Δ
src/model/system.js	80.95% <90.00%> (+80.95%)	⬆️
src/model/project.js	100.00% <100.00%> (ø)
src/model/versioning.js	97.10% <100.00%> (+13.76%)	⬆️

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