fix(#127): Handle relative path in cmd on windows

[sudo-suhas]

This uses path.normalize in commandConvert to handle relative paths like ./cmd.bat on windows.
Also updates the test converts embedded unix-style env variables usage for windows to use path.normalize so that it does not fail on windows.

I have added myself to contributors.

Closes #127

[codecov]

Codecov Report

Merging #130 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #130   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           3      3           
  Lines          50     50           
=====================================
  Hits           50     50

Impacted Files	Coverage Δ
src/command.js	100% <100%> (ø)	⬆️

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[kentcdodds]

Sounds great! Thanks!

[weizhenye]

It seems this PR breaks URL.
My script:
cross-env NODE_ENV=development webpack-dev-server --env.api="https://api.example.com"

path.normalize('https://api.example.com'); // -> 'https:\\api.example.com'

[sudo-suhas]

@weizhenye I think you are right. I am working on a fix.