run Windows on TravisCI

[bicycle1885]

Try this https://discourse.julialang.org/t/julia-is-now-available-on-travis-windows-builds/27187 before forgetting it.

[codecov-io]

Codecov Report

Merging #46 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #46   +/-   ##
=======================================
  Coverage   89.83%   89.83%           
=======================================
  Files           4        4           
  Lines         118      118           
=======================================
  Hits          106      106           
  Misses         12       12

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