Database covariate storage

[azimov]

Resolves PR #152 , storing results in DB rather than Andromeda object. Also fixes likely errors that occured before and allows specification to store timeRef and covariatesContinuous in database tables with newly specified targetTables list parameter.

[codecov]

Codecov Report

Merging #153 (9bc11c9) into develop (fdfd9b7) will increase coverage by 72.47%.
The diff coverage is 96.47%.

@@             Coverage Diff              @@
##           develop     #153       +/-   ##
============================================
+ Coverage    23.28%   95.76%   +72.47%     
============================================
  Files           13       15        +2     
  Lines         1095     1157       +62     
============================================
+ Hits           255     1108      +853     
+ Misses         840       49      -791     

Impacted Files	Coverage Δ
R/Aggregation.R	100.00% <ø> (+100.00%)	⬆️
R/FeatureExtraction.R	60.00% <ø> (+40.00%)	⬆️
R/GetCovariates.R	89.85% <ø> (+27.53%)	⬆️
R/Normalization.R	100.00% <ø> (+27.67%)	⬆️
R/CovariateData.R	88.15% <66.66%> (+78.69%)	⬆️
R/DefaultCovariateSettings.R	94.44% <66.66%> (+0.32%)	⬆️
R/DefaultTemporalCovariateSettings.R	94.44% <66.66%> (+0.32%)	⬆️
R/DefaultTemporalSequenceCovariateSettings.R	94.44% <94.44%> (ø)
R/UnitTestHelperFunctions.R	95.34% <95.34%> (ø)
R/CompareCohorts.R	95.06% <100.00%> (+95.06%)	⬆️
... and 16 more

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[anthonysena]

@azimov - could you merge in the latest code on develop to this branch and resolve any conflicts? Then @ginberg and I will take a look. Thanks!