update for Node.js v12

remove README_BUILD_WINDOWS.md

change require() for packaging

fix typo

update README.md for Node.js V8/V10 with SWIG 4.0.0

update for 0.8.1

update the 4th argument for calling freeargStoreMultiPut()

change Multi-Put/Get/Query from (not available) to (available)

add "npm install nan" in Build and Run

add resolve() in an async method "dropContainer"