Refactor to put rich output formatting in the app namespace

[ponyisi]

#654 added result printout functionality directly into the deliver() function, which will change the behavior quite significantly for people using the API directly. Refactor this code to CLI responsibility.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.15%. Comparing base (c4edadc) to head (6b17ca4).
⚠️ Report is 6 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #675      +/-   ##
==========================================
- Coverage   98.15%   98.15%   -0.01%     
==========================================
  Files          29       29              
  Lines        2061     2060       -1     
==========================================
- Hits         2023     2022       -1     
  Misses         38       38              

Flag	Coverage Δ
unittests	98.15% <100.00%> (-0.01%)	⬇️

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[gordonwatts]

Looks good - some possible suggestions for a future PR