Add Travis-CI Windows build

[kdheepak]

No description provided.

[codecov]

Codecov Report

Merging #5 into master will decrease coverage by 0.75%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master       #5      +/-   ##
==========================================
- Coverage   67.36%   66.61%   -0.76%     
==========================================
  Files           7        7              
  Lines         619      635      +16     
==========================================
+ Hits          417      423       +6     
- Misses        202      212      +10

Impacted Files	Coverage Δ
src/CEnum.jl	72.72% <0%> (-11.89%)	⬇️
src/api.jl	64.91% <0%> (+0.23%)	⬆️

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