Add error for running server as root

[jcpunk]

The DE server should never be run as root. There are a ton of good reasons to forbid this.

[codecov]

Codecov Report

Merging #534 (0665ce9) into master (c4fc599) will increase coverage by 0.16%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #534      +/-   ##
==========================================
+ Coverage   83.54%   83.70%   +0.16%     
==========================================
  Files          47       47              
  Lines        3081     3081              
  Branches      430      430              
==========================================
+ Hits         2574     2579       +5     
+ Misses        467      465       -2     
+ Partials       40       37       -3     

Flag	Coverage Δ
python-3.6	83.00% <ø> (ø)
python-3.9	83.17% <ø> (ø)
python-pypy-3.7	83.30% <ø> (+0.16%)	⬆️

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Impacted Files	Coverage Δ
.../decisionengine/framework/engine/DecisionEngine.py	90.73% <ø> (+0.51%)	⬆️
...ecisionengine/framework/taskmanager/TaskManager.py	96.48% <0.00%> (-0.02%)	⬇️
src/decisionengine/framework/dataspace/maintain.py	99.04% <0.00%> (+0.95%)	⬆️
src/decisionengine/framework/engine/Workers.py	90.27% <0.00%> (+2.77%)	⬆️

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