Added support to read arguments from npm env variables

[hokiedsp]

This PR adds

argparse.env('npm_config_');

to grab the npm config env variables. This feature mimics node-gyp's (implemented around Line 150 in lib/node-gyp.js), and has been tested with electron runtime setup:

https://electronjs.org/docs/tutorial/using-native-node-modules

A couple other related changes:

• dist-url/disturl alias is added
• double quotes around the values of NODEJS_URL and NODEJS_NAME are removed as the quotation marks remain in the defined strings in CMake.