add method to handle level as integers

[jd-lara]

closes #262

[codecov[bot]]

Codecov Report

Merging #263 (916221c) into master (9833e9f) will decrease coverage by 0.76%. The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master     #263      +/-   ##
==========================================
- Coverage   78.47%   77.70%   -0.77%     
==========================================
  Files          43       43              
  Lines        3544     3342     -202     
==========================================
- Hits         2781     2597     -184     
+ Misses        763      745      -18     

Flag	Coverage Δ
unittests	77.70% <50.00%> (-0.77%)	:arrow_down:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/utils/logging.jl	90.85% <50.00%> (-1.62%)	:arrow_down:
src/time_series_utils.jl	70.00% <0.00%> (-5.00%)	:arrow_down:
src/InfrastructureSystems.jl	80.00% <0.00%> (-3.34%)	:arrow_down:
src/utils/utils.jl	64.28% <0.00%> (-1.87%)	:arrow_down:
src/utils/print.jl	51.59% <0.00%> (-1.61%)	:arrow_down:
src/time_series_storage.jl	77.77% <0.00%> (-1.54%)	:arrow_down:
src/utils/generate_structs.jl	84.54% <0.00%> (-1.05%)	:arrow_down:
src/time_series_formats.jl	72.04% <0.00%> (-1.04%)	:arrow_down:
src/internal.jl	78.84% <0.00%> (-0.79%)	:arrow_down:
... and 23 more