Issue 126 methods to generate metadata

[JDTheRipperPC]

Resolves #126

Updated metadata methods and added metadata integration tests.

[codecov-io]

Codecov Report

Merging #132 into master will decrease coverage by 0.02%.
The diff coverage is 83.33%.

@@            Coverage Diff             @@
##           master     #132      +/-   ##
==========================================
- Coverage   88.42%   88.39%   -0.03%     
==========================================
  Files           9        9              
  Lines         570      672     +102     
==========================================
+ Hits          504      594      +90     
- Misses         66       78      +12

Impacted Files	Coverage Δ
sdv/sampler.py	89.52% <100%> (+0.22%)	⬆️
sdv/modeler.py	85.56% <100%> (ø)	⬆️
sdv/sdv.py	83.72% <25%> (-4.09%)	⬇️
sdv/demo.py	91.66% <80%> (+58.33%)	⬆️
sdv/metadata.py	86.31% <84.31%> (-1.34%)	⬇️

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