use library of utility function for platform logic

[Lewiscowles1986]

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Looking at enabling this for linux it really needs one source of truth for determining platform. and for that single-source to be easily maintained.

I made https://github.com/Lewiscowles1986/node-platform for this purpose as it seemed other options did a little too much.

I'd like to make the changes as part of #2 but it should benefit the whole app in-case additional platforms or specific work around for a platform need to be added in future.