improve node-pre-gyp support

[mmomtchev]

• allows searching for node-pre-gyp when it is not installed in the main package node_modules - often it will be in node_modules/native_module/node_modules
• removes the node-pre-gyp require which pulls AWS S3 dependencies
• actually documents this very useful feature that I found about only when I decided to implement it myself :-)

[mmomtchev]

@danielgindi this PR fixes a certain number of native modules (including mine - gdal-async)

[danielgindi]

@danielgindi this PR fixes a certain number of native modules (including mine - gdal-async)

I have reviewed your PR a long time ago, but you have not responded to any of the comments

[mmomtchev]

Sorry, but I don't see any comments?

[danielgindi]

Sorry, but I don't see any comments?

Sorry, the review was not submitted. Ufff.

[danielgindi]

@mmomtchev
I want to merge this. I'd love it if you put some comments to highlight the different situations you encountered, at the points where the code handles them. We don't want to break anything later.

[mmomtchev]

@danielgindi I commented the two changes

[mmomtchev]

I have been using this in a closed source project for about an year, but now I use it in an open-source project, you can see it here: https://github.com/mmomtchev/xc-db

I am using rollup to bundle my Node.js back-end server so that I do not have to handle node_modules in a production environment. The native module I am using is gdal-async of which I am also the maintainer.