Need to address N-API versioning scheme

[aruneshchandra]

[mhdawson]

Will take this on once the doc lands.

[mhdawson]

Looking at this today. I think we have enough flexibility in how we load the N-API modules that we can introduce any module version checking later on without affecting exsting modules, if this ever needed. Hopefully not.

The only thing missing seems to be a method for an addon to be able to check the level of N-API being supported.