Work-around to have the Kivy DLLs in the installer

[VladimirSvoboda]

Kivy packages contain DLL at unusual locations.
Add specific behavior to embed them in the installer.

[codecov]

Codecov Report

Merging #251 (1911bf1) into master (0e05f3e) will decrease coverage by 1.41%.
The diff coverage is 46.66%.

@@            Coverage Diff             @@
##           master     #251      +/-   ##
==========================================
- Coverage   88.34%   86.92%   -1.42%     
==========================================
  Files           8        8              
  Lines         798      811      +13     
==========================================
  Hits          705      705              
- Misses         93      106      +13     

Impacted Files	Coverage Δ
nsist/wheels.py	87.60% <46.66%> (-3.23%)	⬇️
nsist/util.py	88.88% <0.00%> (-5.56%)	⬇️
nsist/copymodules.py	85.05% <0.00%> (-1.15%)	⬇️
nsist/__init__.py	83.94% <0.00%> (-0.37%)	⬇️

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