Consider replacing UNIXisms for x-platform usage

[rmloveland]

For example, the calls to exec.CommandO that shell out to various things may or may not work in Windows environments.

In order of likely compatibility, from "best" to "worst" (haven't yet tested so these are guesses):

• Git will likely work on Windows fine once it's installed
• cp may not work OOTB in stock Windows environments, but it's reasonably common via MinGW/GoW/etc.
• Shelling out to sh to call the $EDITOR is likely to fail on stock Windows

[rmloveland]

FWIW I don't think you have to care about this Jordan. Just filing to capture. I think patches to fix this will be relatively straightforward, and can be written by someone (like me) who uses Windows as a weekend warrior box or whatever. Can probably also solve via documentation for all but the sh bit.