Add tests for ZeroOne variables with variable bounds

[odow]

Closes #758

[codecov-io]

Codecov Report

Merging #772 into master will increase coverage by 0.11%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #772      +/-   ##
==========================================
+ Coverage   94.34%   94.46%   +0.11%     
==========================================
  Files          57       59       +2     
  Lines        6242     6395     +153     
==========================================
+ Hits         5889     6041     +152     
- Misses        353      354       +1

Impacted Files	Coverage Δ
src/Test/UnitTests/constraints.jl	100% <100%> (ø)	⬆️
src/Benchmarks/Benchmarks.jl	98.71% <0%> (ø)
src/Utilities/CleverDicts.jl	100% <0%> (ø)

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[ccoffrin]

Thanks @odow!!!