use a different way to re-build asmcrypto.js
- when npm 1.4.9 installs asmcrypto, it already includes the asmcrypto.js file upon install which means our rebuild target was never called
- also add some variables to set different NPM and NODE
- make npm install commands more precise to avoid overwriting other deps
add a prepublish script for publishing to npm repos
- rm obsolete references to lib/