Updating normalize.py

[gwaybio]

Standardizing API to accept file as input and output.

Also adding tests for this new functionality

[codecov-io]

Codecov Report

Merging #23 into master will increase coverage by 0.04%.
The diff coverage is 94.73%.

@@            Coverage Diff             @@
##           master      #23      +/-   ##
==========================================
+ Coverage   95.59%   95.63%   +0.04%     
==========================================
  Files          23       23              
  Lines         636      665      +29     
==========================================
+ Hits          608      636      +28     
- Misses         28       29       +1

Impacted Files	Coverage Δ
pycytominer/tests/test_normalize.py	100% <100%> (ø)	⬆️
pycytominer/normalize.py	89.28% <86.66%> (+0.39%)	⬆️

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